Anthracene Derivative, Light-Emitting Element Using the Same, and Light-Emitting Device Using the Same

ABSTRACT

It is an object of the present invention to provide a light emitting element, which is resistant to repetition of an oxidation reaction. It is another object of the invention to provide a light emitting element, which is resistant to repetition of a reduction reaction. An anthracene derivative is represented by a general formula (1). In the general formula (1), R1 represents hydrogen or an alkyl group having 1 to 4 carbon atoms, R2 represents any one of hydrogen, an alkyl group having 1 to 4 carbon atoms and an aryl group having 6 to 12 carbon atoms, R3 represents any one of hydrogen, an alkyl group having 1 to 4 carbon atoms, and an aryl group having 6 to 12 carbon atoms, Ph1 represents a phenyl group, and X1 represents an arylene group having 6 to 15 carbon atoms.

TECHNICAL FIELD

The present invention relates to an anthraccne derivative, and inparticular, relates to an anthracene derivative that can be used as amaterial for manufacturing a light emitting element.

BACKGROUND ART

In recent years, many of light emitting elements used for displays andthe like have a structure in which a layer containing a light emittingsubstance is interposed between a pair of electrodes. Such lightemitting elements emit light when an exciton that is generated byrecombination of an electron injected from one electrodes and a holeinjected from the other electrodes returns to a ground state.

In order to obtain a light emitting element having an excellent lightemitting efficiency and good chromaticity or a light emitting elementthat can prevent optical quenching and the like, various researchesabout substances that can be used as materials for manufacturing such alight emitting element have been carried out in the field of lightemitting elements.

For example, the patent document 1 discloses a material for an organicEL element having an excellent light emitting efficiency and long termdurability.

Meanwhile, in a light emitting element, a current flows betweenelectrodes by transportation of holes or electrons. In this case, alight emitting substance that receives holes or electrons or the like,or, a light emitting substance that is oxidized or reduced or the likesometimes does not return to a neutral state and is changed to adifferent substance having a different property and a differentstructure. When the changes of the property and structure of the lightemitting substance are accumulated, a characteristic of the lightemitting element may also be changed.

Therefore, there are high expectations for a development of a lightemitting substance of which a property is difficult to be changed due tooxidation or reduction.

Patent Document 1: Japanese Patent Application Laid-Open No.2001-131541.

DISCLOSURE OF INVENTION

It is an object of the present invention to provide a substance that hashigh resistance to repetition of an oxidation reaction and can be usedas a material for a light emitting element. Moreover, it is anotherobject of the invention to provide a light emitting element and a lightemitting device each in which deterioration in an operationalcharacteristic of the light emitting element due to change in acharacteristic of a substance caused by repetition of an oxidationreaction is reduced.

An aspect of the present invention is an anthracene derivativerepresented by a general formula (1)

In the general formula (1), R¹ represents either hydrogen or an alkylgroup having 1 to 4 carbon atoms. R² represents any one of hydrogen, analkyl group having 1 to 4 carbon atoms and an aryl group having 6 to 12carbon atoms. The aryl group may have a substituent or no substituent.R³ represents any one of hydrogen an alkyl group having 1 to 4 carbonatoms, and an aryl group having 6 to 12 carbon atoms. The aryl group mayhave a substituent or no substituent. Ph¹ represents a phenyl group. Thephenyl group may have a substituent or no substituent. X¹ represents anarylene group having 6 to 15 carbon atoms. The arylene groups may has asubstituent or no substituent.

Another aspect of the present invention is an anthracene derivativerepresented by a general formula (2).

In the general formula (2), R⁴ represents either hydrogen or an alkylgroup having 1 to 4 carbon atoms. R⁵ and R⁶ represent hydrogen, or,aromatic rings which are bonded to each other, and R⁷ and R⁸ representhydrogen, or, aromatic rings which are bonded to each other. R⁹represents any one of hydrogen, an alkyl group having 1 to 4 carbonatoms, and an aryl group having 6 to 12 carbon atoms. The aryl group mayhave a substituent or no substituent. R¹⁰ represents any one ofhydrogen, an alkyl group having 1 to 4 carbon atoms, and an aryl grouphaving 6 to 12 carbon atoms. The aryl group may have a substituent or nosubstituent. Ph² represents a phenyl group. The phenyl group may have asubstituent or no substituent.

Another aspect of the present invention is an anthracene derivativerepresented by a general formula (3).

In the general formula (3), R¹¹ represents either hydrogen or an alkylgroup having 1 to 4 carbon atoms. R¹² represents any one of hydrogen, analkyl group having 1 to 4 carbon atoms, and an aryl group having 6 to 12carbon atoms. The aryl group may have a substituent or no substituent.R¹³ represents any one of hydrogen, an alkyl group having 1 to 4 carbonatoms, and an aryl group having 6 to 12 carbon atoms. The aryl group mayhave a substituent or no substituent. Ph³ represents a phenyl group. Thephenyl group may have a substituent or no substituent.

Another aspect of the present invention is an anthracene derivativerepresented by a general formula (4).

In the general formula (4), R¹⁴ represents any one of hydrogen, an alkylgroup having 1 to 4 carbon atoms, and an aryl group having 6 to 12carbon atoms. The aryl group may have a substituent or no substituent.R¹⁵ represents any one of hydrogen, an alkyl group having 1 to 4 carbonatoms, and an aryl group having 6 to 12 carbon atoms. The aryl group mayhave a substituent or no substituent. Ph⁴ represents a phenyl group. Thephenyl group may have a substituent or no substituent.

Another aspect of the present invention is an anthracene derivativerepresented by a general formula (5).

In the general formula (5), R¹⁶ represents either hydrogen or an alkylgroup having 1 to 4 carbon atoms.

Another aspect of the present invention is an anthracene derivativerepresented by a general formula (6).

In the general formula (6), X² represents an arylene group having 6 to15 carbon atoms. The arylene group may have a substituent or nosubstituent.

Another aspect of the present invention is an anthracene derivativerepresented by a general formula (7).

In the general formula (7), R¹⁷ represents any one of hydrogen, an alkylgroup having 1 to 4 carbon-atoms, and an aryl group having 6 to 12carbon atoms. The aryl group may have a substituent or no substituent.

Another aspect of the present invention is an anthracene derivativerepresented by a general formula (8).

In the genera formula (8), R¹⁸ represents any one of hydrogen, an alkylgroup having 1 to 4 carbon atoms, and an aryl group having 6 to 12carbon atoms. The aryl group may have a substituent or no substituent.

Another aspect of the present invention is a light emitting element thathas a layer containing an anthracene derivative represented by any oneof the general formulas (1) to (8), between electrodes.

Another aspect of the present invention is a light emitting device usinga light emitting element containing an anthracene derivative representedby any one of the general formulas (1) to (8).

Another aspect of the present invention is a light emitting device thathas a light emitting element containing an anthracene derivativerepresented by any one of the general formulas (1) to (8), in a pixelportion.

Another aspect of the present invention is an electronic appliancemounted with a light emitting device that uses a light emitting elementcontaining an anthracene derivative represented by any one of thegeneral formulas (1) to (8).

In accordance with the present invention, a substance being highlyresistant to repetition of an oxidation reaction, which can be used as amaterial for manufacturing a light emitting element, can be obtained. Inaddition, in accordance with the present invention, it is possible toobtain a substance being highly resistant to repetition of an oxidationreaction and repetition of a reduce reaction, which can be used as amaterial for manufacturing a light emitting element.

By implementing the present invention, it is possible to obtain a lightemitting element in which deterioration in an element characteristiccaused by repetition of an oxidation reaction of a substance, which isused in a layer provided between electrodes, can be reduced. It is alsopossible to obtain a light emitting element that can stably emit lightfor a long time and has less changes in a characteristic of the lightemitting element cased with change in a property of a light emittingsubstance due to repetition of an oxidation reaction.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a cross sectional view explaining a light emitting element ofthe present invention;

FIG. 2 is a cross sectional view explaining a light emitting element ofthe present invention;

FIG. 3 is a top view explaining a light emitting device to which thepresent invention is applied;

FIG. 4 is a diagram explaining a circuit included in a light emittingdevice to which the present invention is applied;

FIG. 5 is a top view of a light emitting device to which the presentinvention is applied;

FIG. 6 is a diagram explaining a flame operation of a light emittingdevice to which the present invention is applied;

FIG. 7 is a diagram explaining a circuit included in a light emittingdevice to which the present invention is applied;

FIGS. 8A to 8C are cross sectional views of a light emitting device towhich the present invention is applied;

FIGS. 9A to 9C are diagrams of electronic appliances to which thepresent invention is applied;

FIG. 10 is a graph showing an absorption spectrum of an anthracenederivative of the present invention;

FIG. 11 is a graph showing an absorption spectrum of an anthracenederivative of the present invention;

FIGS. 12A and 12B are graphs showing measurement results by cyclicvoltammetry (CV) of an anthraccne derivative of the present invention;

FIGS. 13A and 13B are ¹H-NMR charts of PCA synthesized in SyntheticExample 1;

FIGS. 14A and 14B are ¹H-NMR charts of PCABPA synthesized in SyntheticExample 1;

FIG. 15 is a cross sectional view explaining a light emitting elementmanufactured in an embodiment;

FIG. 16 is a graph showing a luminance-voltage characteristic of a lightemitting element manufactured in Embodiment 2;

FIG. 17 is a graph showing a luminance-current efficiency characteristicof a light emitting element manufactured in Embodiment 2;

FIG. 18 is a graph showing a light emission spectrum of a light emittingelement manufactured in Embodiment 2;

FIG. 19 is a graph showing a luminance-voltage characteristic of a lightemitting element manufactured in Embodiment 3;

FIG. 20 is a graph showing a luminance-current efficiency characteristicof a light emitting element manufacturing in Embodiment 3;

FIG. 21 is a graph showing a light emission spectrum of a light emittingelement manufactured in Embodiment 3;

FIG. 22 is a graph showing a luminance-voltage characteristic of a lightemitting element manufactured in Embodiment 4;

FIG. 23 is a graph showing a luminance-current efficiency characteristicof a light emitting element manufactured in Embodiment 4;

FIG. 24 is a graph showing a light emission spectrum of a light emittingelement manufactured in Embodiment 4;

FIG. 25 is a graph showing a luminance-voltage characteristic of a lightemitting element manufacturing in Embodiment 5;

FIG. 26 is a graph showing a luminance-current efficiency characteristicof a light emitting element manufacturing in Embodiment 5;

FIG. 27 is a graph showing a light emission spectrum of a light emittingelement manufactured in Embodiment 5;

FIG. 28 is a graph showing a luminance-voltage characteristic of a lightemitting element manufacturing in Embodiment 6;

FIG. 29 is a graph showing a luminance-current efficiency characteristicof a light emitting element manufacturing in Embodiment 6;

FIG. 30 is a graph showing a light emission spectrum of a light emittingelement manufactured in Embodiment 6;

FIG. 31 is a graph showing a luminance-voltage characteristic of a lightemitting element manufacturing in Embodiment 7;

FIG. 32 is a graph showing a luminance-current efficiency characteristicof a light emitting element manufacturing in Embodiment 7;

FIG. 33 is a graph showing a light emission spectrum of a light emittingelement manufactured in Embodiment 7;

FIG. 34 is a graph showing a luminance-voltage characteristic of a lightemitting element manufacturing in Embodiment 8;

FIG. 35 is a graph showing a luminance-current efficiency characteristicof a light emitting element manufacturing in Embodiment 8;

FIG. 36 is a graph showing a light emission spectrum of a light emittingelement manufactured in Embodiment 8;

FIG. 37 is a graph showing a luminance-voltage characteristic of a lightemitting element manufacturing in Embodiment 9;

FIG. 38 is a graph showing a luminance-current efficiency characteristicof a light emitting element manufacturing in Embodiment 9;

FIG. 39 is a graph showing a light emission spectrum of a light emittingelement manufactured in Embodiment 9;

FIG. 40 is a graph showing a luminance-voltage characteristic of a lightemitting element manufacturing in Embodiment 10;

FIG. 41 is a graph showing a luminance-current efficiency characteristicof a light emitting element manufacturing in Embodiment 10;

FIG. 42 is a graph showing a light emission spectrum of a light emittingelement manufactured in Embodiment 10;

FIG. 43 is a graph showing a luminance-voltage characteristic of a lightemitting element manufacturing in Embodiment 11;

FIG. 44 is a graph showing a luminance-current efficiency characteristicof a light emitting element manufacturing in Embodiment 11;

FIG. 45 is a graph showing a light emission spectrum of a light emittingelement manufactured in Embodiment 11;

FIG. 46 is a diagram explaining a mode of a light emitting device of thepresent invention;

FIGS. 47A and 47B are ¹H-NMR charts of PCABBA synthesized in SyntheticExample 2;

FIG. 48 is a graph showing an absorption spectrum of an anthracenederivative of the present invention; and

FIG. 49 is a graph showing a light emission spectrum of an anthracenederivative of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

The embodiment modes according to the present invention will hereinafterbe described. It is easily understood by those skilled in the art thatthe embodiment modes and details herein disclosed can be modified invarious ways without departing from the purpose and the scope of theinvention. The present invention should not be interpreted as beinglimited to the description of the embodiment modes to be given below.

Embodiment Mode 1

A mode of an anthracene derivative of the present invention will bedescribed.

As an anthracene derivative of the present invention, anthracenederivatives represented by the following structural formulas (1) to (40)can be given.

These anthracene derivatives can be obtained by, for example, performinga coupling reaction of a compound A containing anthracene such as9,10-dibromo arylanthracne in a skeleton and a compound B containingarylamino carbazole in a skeleton, as represented by the followingsynthetic scheme (a-1). Further, a method for synthesizing an anthracenederivative of the present invention is not limited to the syntheticmethod described here and the anthracene derivative of the invention canbe synthesized by other synthetic method.

In the synthetic scheme (a-1), R¹⁹ represents either hydrogen ortert-buty. R²⁰ represents one group selected from alkyl groups having 1to 4 carbon atoms such as hydrogen, methy, ethyl and tert-butyl, andaryl groups having 1 to 12 carbon atoms such as phenyl, biphenyl andnaphthyl. Further, the aryl group may have a substituent or nosubstituent. Ph⁵ represents a phenyl group. The phenyl group may have asubstituent or no substituent. X³ represents an arylene group having 6to 15 carbon atoms such as phenylene, naphthylene, anthrylene, and9,9-dimethylfluorene-2,7-diyl.

The compound A can be obtained using dibromoarene (a compound C) and acompound containing anthraquinone in a skeleton as main raw materials,as represented by a synthetic scheme (a-2). Also, the compound B can beobtained by substituting bromo for hydrogen at a three position of acompound that contains carbazole in a skeleton, and then by performing areaction such that an amino group is substituted for the bromo, asrepresented by a synthetic scheme (a-3).

Although 9,10-bis(bromoaryl) anthracene is used as the compound A, whichhas an anthracene skeleton, in this embodiment mode, 9,10-bis(odoaryl)anthracene or the like may also be used. In the synthetic scheme (a-2),the 9,10-bis(iodoaryl) anthracene can be obtained by using diiodoarenesuch as 1,5-diiodonaphthalene and 2,7-diiodo-9,9-dimethylfluorene assubstitute for the compound C. Furthermore, the 1,5-diiodonaphthalene,the 2,7-diiodo-9,9-dimethylfluorene and the like can be obtained byperforming a synthesis in the following manner. Firstly, the1,5-diiodonaphthalene can be obtained as follows: an amino groupcontained in 1,5-diaminonaphthalene is changed to diazonium salt usingsodium nitrite and concentrated sulfuric acid, and the diazonium salt issubstituted for iodine using potassium iodide. Further, the2,7-diiodo-9,9-dimethylfluorene can be obtained as follows: a secondposition and a seventh position of fluorene are iodized by usingorthoperiodic acid, and then a ninth position of the iodized fluorene isdimethylized in dimethylsulfoxide (abbreviation: DMSO) by using a sodiumhydroxide solution, benzyltimethylammonium chloride, and iodomethane.

As set forth above, an anthracene derivative of the present invention isresistant to repetition of an oxidation reaction. The anthracenederivative is sometimes also resistant to repetition of a reductionreaction as well as the repetition of the oxidation reaction. Inaddition, the anthracene derivative of the present invention describedabove can emit blue light. Therefore, the anthracene derivative can beused as a light emitting substance for manufacturing a blue lightemitting element. Since the anthracene derivative of the presentinvention as described above has a large energy gap between the HOMOlevel and the LUMO level, it can be used as a substance for dispersing alight emitting substance, which emits red light to blue light, or, ahost material. Utilizing the anthracene derivative of the presentinvention as a light emitting substance or a host material makes itpossible to obtain a light emitting element having less changes in ahost property due to repetition of an oxidation reaction, wherein theincrease in driving voltage with an accumulation of light emitting timeand the like are reduced.

Embodiment Mode 2

One mode of a light emitting element using an anthracene derivative ofthe present invention as a light emitting substance will be describedwith reference to FIG. 1.

A light emitting element having a light emitting layer 113 between afirst electrode 101 and a second electrode 102 is shown in FIG. 1. Thelight emitting layer 113 contains an anthracene derivative of thepresent invention represented by any one of the general formulas (1) to(8) and the structural formulas (1) to (40).

In such a light emitting element, a hole injected from the firstelectrode 101 and an electron injected from the second electrode 102 arerecombined at the light emitting layer 113, which makes the anthracenederivative of the present invention excited. The anthracene derivativeof the present invention in the excited state emits light upon returningto a ground state. Thus, the anthracene derivative of the presentinvention serves as a light emitting substance.

The light emitting layer 113 is preferably a layer in which ananthracene derivative of the present invention represented by any one ofthe general formulas (1) to (8) and the structural formulas (1) to (40)is dispersed in a substance having a larger energy gap than that of theanthracene derivative of the present invention. This can prevent lightemitted from the anthracene derivative of the present invention fromgoing out due to the concentration. Further, the energy gap indicates anenergy gap between the LUMO level and the HOMO level.

Although a substance used for dispersing the anthracene derivative ofthe present invention is not particularly limited, a metal complex suchas bis[2-(2-hydroxyphenyl)pyridinato] zinc (abbreviation: Znpp₂) andbis[2-(2-hydroxyphenyl) benazoxazolato] zinc (abbreviation: Zn(BOX)₂),and the like are preferable, in addition to an anthracene derivativesuch as 2-tert-butyl-9,10-di(2-naphthyl) anthracene (abbreviation:t-BuDNA) and a carbazole derivative such as 4,4′-di(N-carbazolyl)biphenyl (abbreviation: CBP). One or more substances may be selectedfrom the above mentioned substances and mixed in an anthracenederivative of the present invention so as to disperse the anthracenederivative of the invention in the one or more substances. Such a layerin which a plurality of compounds are mixed can be formed by usingco-evaporation. The co-evaporation is an evaporation method in which rawmaterials are respectively vaporized from a plurality of evaporationsources provided in one processing chamber and the vaporized rawmaterials are mixed in a gaseous state so as to be deposited over anobject material.

Also, the first electrode 101 and the second electrode 102 are notparticularly limited. They can be formed by using gold (Au), platinum(Pt), nickel (Ni), tungsten (W), chromium (Cr), molybdenum (Mo), iron(Fe), cobalt (Co), copper (Cu), palladium (Pd) and the like, in additionto indium tin oxide (ITO), indium tin oxide containing silicon oxide andindium oxide containing 2 to 20 wt % zinc oxide. The first electrode 101can also be formed using an alloy of magnesium and silver, an alloy ofaluminum and lithium or the like, in addition to aluminum. Further amethod for forming the first electrode 101 and the second electrode 102is not particularly limited. For example, they can be formed by usingsputtering, evaporation or the like. To emit light to an externalportion, one or both of the first electrode 101 and the second electrode102 is/are preferably formed by using indium tin oxide or the like, orusing silver, aluminum or the like to have a thickness of several am toseveral teas nm such that visible light is transmitted therethrough.

As shown in FIG. 1, a hole transporting layer 112 may be providedbetween the first electrode 101 and the light emitting layer 113. Thehole transporting layer is a layer having a function of transportingholes injected from the first electrode 101 to the light emitting layer113. Thus, providing the hole transporting layer 112 makes it possibleto increase a distance between the first electrode 101 and the lightemitting layer 113. As a result, it is possible to prevent lightemission from going out due to a metal contained in the first electrode101 and the like. The hole transporting layer is preferably formed usinga substance having a strong hole transporting property. In particular, asubstance having hole mobility with 1×10⁻⁶ cm²/Vs or more is preferablyused for forming the hole transporting layer. Further, the substancehaving the strong hole transporting property is a substance of whichhole mobility is stronger than electron mobility and a ratio of the holemobility to the electron mobility (i.e., the hole mobility/the electronmobility) is 100 or more. As a specific example of a substance that canbe used for forming the hole transporting layer 112,4,4′-bis[N-(1-naphthyl)-N-phenylamino] biphenyl (abbreviation: NPB),4,4′-bis[N-(3-methylphenyl)-N-phenylamino] biphenyl (abbreviation: TPD),4,4′,4″-tris(N,N-diphenylamino) triphenylamine (abbreviation: TDATA),4,4′,4″-tris[N-(3-methylphenyl)-N-phenylamino] triphenylamine(abbreviation: MTDATA), 4,4′-bis{N-[4-(N,N-di-m-tolylamino)phenyl]-N-phenyl-amino} biphenyl (abbreviation: DNTPD),1,3,5-tris[N,N-di(m-tolyl)amino] benzene (abbreviation: m-MTDAB),4,4′,4″-tris(N-carbazolyl) triphenylamine (abbreviation: TCTA),phthalocyanine (abbreviation: H₂Pc), copper phthalocyanine(abbreviation: CuPc), vanadyl phthalocyanine (abbreviation: VOPc), andthe like can be given. Further, the hole transporting layer 112 may be alayer having a multilayer structure that is formed by combining two ormore layers including the above mentioned substances.

Also, as shown in FIG. 1, an electron transporting layer 114 may beprovided between the second electrode 102 and the light emitting layer113. The electron transporting layer is a layer having a function oftransporting electrons injected from the second electrode 102 to thelight emitting layer 113. Thus, providing the electron transportinglayer 114 makes it possible to increase a distance between the secondelectrode 102 and the light emitting layer 113. As a result, it ispossible to prevent light emission from going out due to a metalcontained in the second electrode 102 and the like. The electrontransporting layer is preferably formed using a substance having astrong electron transporting property. In particular, a substance havingelectron mobility with 1×10⁻⁶ cm²/Vs or more is preferably used forforming the electron transporting layer. Further the substance havingthe strong electron transporting property is a substance of whichelectron mobility is stronger than hole mobility and a ratio of theelectron mobility to the hole mobility (i.e., the electron mobility/thehole mobility) is 100 or more. As a specific example of a substance thatcan be used for forming the electron transporting layer 114, a metalcomplex such as tris(8-quinolinolato) aluminum (abbreviation: Alq₃),tris(4-methyl-8-quinolinolato) aluminum (abbreviation: Almq₃),bis(10-hydroxybenzo[h]-quinolinato) beryllium (abbreviation: BeBq₂),bis(2-methyl-8-quinolinolato)-4-phenylphenolate-aluminum (abbreviation:BAlq), bis[2-(2-hydroxyphenyl) benzoxazolato] zinc (abbreviation:Zn(BOX)₂), and bis[2-(2-hydroxyphenyl) benzothiazolato] zinc(abbreviation: Zn(BTZ)₂) can be given. In addition,2-(4-biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (abbreviation:PBD), 1,3-bis[5-(p-tert-butylphenyl)-1,3,4-oxadiazole-2-yl] benzene(abbreviation OXD-7),3-(4-tert-butylphenyl)-4-phenyl-5-(4-biphenylyl)-1,2,4-triazole(abbreviation: TAZ),3,4-tert-butylphenyl)-4-(4-ethylphenyl)-5-(4-biphenylyl)-1,2,4-triazol(abbreviation: p-ETAZ), bathophenanthroline (abbreviation: BPhen),bathocuproin (abbreviation: BCP), 4,4-bis(5-methylbenzoxazole-2-yl)stilbene (abbreviation: BzOs) and the like can be given. Further, theelectron transporting layer 114 may be a layer having a multilayerstructure that is formed by combining two or more layers including theabove mentioned substances.

Each of the hole transporting layer 112 and the electron transportinglayer 114 may be formed using a bipolar substance, in addition to theabove mentioned substances. The bipolar substance is a substance ofwhich when comparing electron mobility and hole mobility, a ratio of themobility of one carrier to the mobility of the other carrier is 100 orless, and preferably, 10 or less. As the bipolar substance, for example,2,3-bis(4-diphenylaminophenyl) quinoxaline (abbreviation: TPAQn) and thelike can be given. Among bipolar substances, in particular, a substancehaving hole and electron mobility with 1×10⁻⁶ cm²N/Vs or more ispreferably used. Also, the hole transporting layer 112 and the electrontransporting layer 114 may be formed using the same bipolar substance.

As shown in FIG. 1, a hole injecting layer 111 may also be providedbetween the first electrode 101 and the hole transporting layer 112. Thehole injecting layer 111 is a layer having a function of helpinginjection of holes to the hole transporting layer 112 from the firstelectrode 101. Providing the hole injecting layer 111 makes it possibleto reduce the difference in ionization potential between the firstelectrode 101 and the hole transporting layer 112 so that holes areeasily injected. The hole injecting layer 111 is preferably formed byusing a substance of which an ionization potential is lower than that ofa substance of the hole transporting layer 112 and higher than that of asubstance used for forming the first electrode 101, or a substance inwhich an energy band is bent when it is provided as a thin film with athickness of 1 to 2 nm between the hole transporting layer 112 and thefirst electrode 101. As a specific example of a substance that can beused for forming the hole injecting layer 111, a phthalocyanine compoundsuch as phthalocyanine (abbreviation: H₂Pc) and copper phthalocyanine(abbreviation: CuPc), a polymer such as apoly(ethylenedioxythiophene)/poly(styrenesulfonate) aqueous solution(abbreviation: PEDOT/PSS), and the like can be given. That is, the holeinjecting layer 111 can be formed by selecting a substance by which anionization potential in the hole injecting layer 111 is relativelysmaller than an ionization potential of the hole transporting layer 112from substances having hole transporting properties. Further whenproving the hole injecting layer 111, the first electrode 101 ispreferably formed using a substance having a high work function such asindium tin oxide.

An electron injecting layer 115 may also be provided between the secondelectrode 102 and the electron transporting layer 114 as shown inFIG. 1. The electron injecting layer 115 is a layer having a function ofhelping injection of electrons to the electron transporting layer 114from the second electrode 102. Providing the electron injecting layer115 makes it possible to reduce the difference in electron affinitybetween the second electrode 102 and the electron transporting layer 114so that electrons are easily injected. The electron injecting layer 115is preferably formed using a substance of which an electron affinity ishigher than that of a substance included in the electron transportinglayer 114 and lower than that of a substance included in the secondelectrode 102, or a substance of which an energy band is bent when it isprovided as a thin film with a thickness of 1 to 2 nm between theelectron transporting layer 114 and the second electrode 102. As aspecific example of a substance that can be used for forming theelectron injecting layer 115, inorganic materials such as alkali metal,alkali earth metal, fluoride of alkali metal, fluoride of alkali earthmetal, alkali metal oxide, and alkali earth metal oxide can be given. Inaddition to the inorganic materials, among the substances, which can beused for forming the electron transporting layer 114, such as BPhen,BCP, p-EtTAZ, TAZ and BzOs, a substance having higher electron affinitythan that of a substance used for forming the electron transportinglayer 114 can be selected to be used to form the electron injectinglayer 115. That is, a substance by which an electron affinity of theelectron injecting layer 115 is relatively higher than that of theelectron transporting layer 114, is selected from substances havingelectron transporting properties so that the electron injecting layer115 can be formed. Further, when providing the electron injecting layer115, the first electrode 101 is preferably formed using a substancehaving a low work function such as aluminum.

In the light emitting element of the present invention as describedabove, the hole injecting layer 111, the hole transporting layer 112,the light emitting layer 113, the electron transporting layer 114, andthe electron injecting layer 115 may be formed by using any method suchas evaporation, ink-jet, and a coating method, respectively. Further,the first electrode 101 and the second electrode 102 may be formed byusing any method such as sputtering and evaporation.

Moreover, a hole generating layer may be provided as a substitute forthe hole injecting layer 111. Alternatively, an electron generatinglayer may be provided as a substitute for the electron injecting layer115.

The hole generating layer is a layer generating holes. The holegenerating layer can be formed by mixing a substance of which holemobility is stronger than electron mobility and a substance exhibitingan electron accepting property with respect to the substance of whichthe hole mobility is stronger than the electron mobility. The holegenerating layer can also be formed by mixing at least one substanceselected from bipolar substances and a substance exhibiting an electronaccepting property with respect to the bipolar substance. As thesubstance of which the hole mobility is stronger than the electronmobility, the same substance as a substance that can be used for formingthe hole transporting layer 112 can be used. As the bipolar substance, abipolar substance such as TPAQn can be used. Also, among substanceshaving stronger hole mobility than electron mobility and bipolarsubstances, in particular, a substance containing triphenylamine inskeleton is preferably used. Using the substance containingtriphenylamine in the skeleton makes it possible to generate holes moreeasily. As the substance exhibiting the electron accepting property,metal oxide such as molybdenum oxide, vanadium oxide, ruthenium oxide,and rhenium oxide is preferably used.

Further, the electron generating layer is a layer generating electrons.The electron generating layer can be formed by mixing a substance ofwhich electron mobility is stronger than hole mobility and a substanceexhibiting an electron donating property with respect to the substanceof which the electron mobility is stronger than the hole mobility. Theelectron generating layer can also be formed by mixing at least onesubstance selected from bipolar substances and a substance exhibiting anelectron donating property with respect to the bipolar substance. Here,as the substance of which the electron mobility is stronger than thehole mobility, the same substance as a substance that can be used forforming the electron transporting layer 114 can be used. As the bipolarsubstance, the above mentioned bipolar substances such as TPAQn can beused. As the substance exhibiting the electron donating property, asubstance selected from alkali metal and alkali earth metal can be used.Specifically, at least one substance selected from lithium oxide (Li₂O),calcium oxide (CaO), natrium oxide (Na₂O), kalium oxide (K₂O), andmagnesium oxide (MgO) can be used as the substance exhibiting theelectron donating property. In addition, alkali metal fluoride or alkaliearth metal fluoride, and specifically, at least one substance selectedfrom lithium fluoride (Li), cesium fluoride (CsF) and calcium fluoride(CaF₂) can be used as the substance exhibiting the electron donatingproperty. Further, alkali metal nitride, alkali earth metal nitride, andthe like, or specifically, at least one substance selected from calciumnitride, magnesium nitride and the like can be used as the substanceexhibiting the electron donating property.

Since the light emitting element of the present invention having theabove described structure uses an anthracene derivative of the presentinvention, there are few changes in a characteristic of the lightemitting element in accordance with changes in a property of a lightemitting substance due to repetition of an oxidation reaction. As aresult, the light emitting element can emit light stably for a longtime. Moreover, since the light emitting element of the presentinvention comprising the above described structure uses an anthracenederivative of the present invention, it can emit light efficiently.

Embodiment Mode 3

When an anthracene derivative of the present invention is included in alight emitting layer along with a light emitting substance, theanthracene derivative can be used as a substance for dispersing thelight emitting substance, or, a host material. In Embodiment Mode 3, amode of a light emitting element using an anthracene derivative of thepresent invention as a host material will be described with reference toFIG. 2.

FIG. 2 shows a light emitting element having a light emitting layer 213between a first electrode 201 and a second electrode 202. A holeinjecting layer 211 and a hole transporting layer 212 are providedbetween the first electrode 201 and the light emitting layer 213 whilean electron transporting layer 214 and an electron injecting layer 215are provided between the second electrode 202 and the light emittinglayer 213. Further, a laminated structure of the light emitting elementis not particularly limited. An operator of the present invention mayarbitrarily determine whether the hole injecting layer 211, the holetransporting layer 212, the electron transporting layer 214, theelectron injecting layer 215 and other layer other than these layers areprovided or not provided. Furthermore, the hole injecting layer 211, thehole transporting layer 212, the electron transporting, layer 214 andthe electron injecting layer 215 may be the same as the hole injectinglayer 111, the hole transporting layer 112, the electron transportinglayer 114 and the electron injecting layer 115 described in EmbodimentMode 2, and therefore these layers will not be further described in thisembodiment mode. Similarly, since the first electrode 201 and the secondelectrode 202 may be the same as the first electrode 101 and the secondelectrode 102 described in Embodiment Mode 1, respectively, they willnot be further described here.

In the light emitting element of this embodiment mode, the lightemitting layer 213 contains an anthracene derivative of the presentinvention and a light emitting substance having a spectrum peak in arange of 450 to 700 nm, and preferably 480 nm to 600 nm. Specifically,the light emitting substance is dispersed in a layer formed using theanthracene derivative of the present invention. By using a combinationof such a substance and the anthracene derivative of the presentinvention, a light emitting element in which light from a host materialis difficult to be mixed and light caused by the light emittingsubstance can be selectively emitted, can be obtained.

Moreover, the anthracene derivative of the present invention isresistant to repetition of an oxidation reaction. Furthermore, theanthracene derivative of the present invention is sometimes resistant torepetition of a reduction reaction, as well as the repetition of theoxidation reaction. Therefore, in the case of a light emitting-elementin which a host material is excited and light is emitted by moving thethus caused excited energy to a light emitting substance, there are fewchanges in a characteristic of the host material due to repetition of anoxidation reaction, and the increase in driving voltage withaccumulation of light emitting time and the like can be reduced.

Embodiment Mode 4

Since the light emitting elements of the present invention described inEmbodiment Modes 2 and 3 are resistant to repetition of an oxidationreaction (which are sometimes also resistant to repetition of areduction reaction) and can emit light stably for a long time, a lightemitting device that can display favorable images for a long time can beobtained by using the light emitting elements of the present invention.

In this embodiment mode, circuit structures and driving methods of alight emitting device having a display function will be described withreference to FIGS. 3, 4, 5 and 6.

FIG. 3 is a schematic top view of a light emitting device to which thepresent invention is applied. In FIG. 3, a pixel portion 6511, a sourcesignal line driver circuit 6512, a writing gate signal line drivercircuit 6513 and an erasing gate signal line driver circuit 6514 areprovided over a substrate 6500. The source signal line driver circuit6512, the writing gate signal line driver circuit 6513 and the erasinggate signal line driver circuit 6514 are respectively connected to FPCs(flexible printed circuits) 6503, which are external input terminals,through wiring groups. The source signal line driver circuit 6512, thewriting gate signal line driver circuit 6513 and the erasing gate signalline driver circuit 6514 receive video signals, clock signals, startsignals, reset signals and the like from the FPCs 6503, respectively.The FPCs 6503 are attached with printed wiring boards (PWBs) 6504.Further a driver circuit portion is not necessary to be formed over thesame substrate as the pixel portion 6511. For example, the drivercircuit portion may be provided outside of the substrate by utilizing aTCP in which an IC chip is mounted over an FPC having a wiring pattern,or the like.

A plurality of source signal lines extending in columns are aligned inrows in the pixel portion 6511. Also, power supply lines are aligned inrows. A plurality of gate signal lines extending in rows are aligned incolumns in the pixel portion 6511. In addition, a plurality of circuitseach including a light emitting element are aligned in the pixel portion6511.

FIG. 4 is a diagram showing a circuit for operating one pixel. Thecircuit as shown in FIG. 4 comprises a first transistor 901, a secondtransistor 902 and a light emitting element 903.

Each of the first and second transistors 901 and 902 is a three terminalelement including a gate electrode, a drain region and a source region.A channel region is interposed between the drain region and the sourceregion. The region serving as the source region and the region servingas the drain region are changed depending on a structure of atransistor, an operational condition and the like so that it isdifficult to determine which region serves as the source region or thedrain region. Therefore, regions serving as the source or the drain aredenoted as a first electrode and a second electrode in this embodimentmode, respectively.

A gate signal line 911 and a writing gate signal line driver circuit 913are provided to be electrically connected or disconnected to each otherby a switch 918. The gate signal line 911 and an erasing gate signalline driver circuit 914 are provided to be electrically connected ordisconnected to each other by a switch 919. A source signal line 912 isprovided to be electrically connected to either a source signal linedriver circuit 915 or a power source 916 by a switch 920. A gate of thefirst transistor 901 is electrically connected to the gate signal line911. The first electrode of the first transistor is electricallyconnected to the source signal line 912 while the second electrodethereof is electrically connected to a gate electrode of the secondtransistor 902. The first electrode of the second transistor 902 iselectrically connected to a current supply line 917 while the secondelectrode thereof is electrically connected to one electrode included inthe light emitting element 903. Further, the switch 918 may be includedin the writing gate signal line driver circuit 913. The switch 919 mayalso be included in the erasing gate signal line driver circuit 914. Inaddition, the switch 920 may be included in the source signal linedriver circuit 915.

The arrangement of transistors, light emitting elements and the like inthe pixel portion is not particularly limited. For example, thearrangement as shown in a top view of FIG. 5 can be employed. In FIG. 5,a first electrode of a first transistor 1001 is connected to a sourcesignal line 1004 while a second electrode of the first transistor isconnected to a gate electrode of a second transistor 1002. A firstelectrode of the second transistor is connected to a current supply line1005 and a second electrode of the second transistor is connected to anelectrode 1006 of a light emitting element. A part of the gate signalline 1003 functions as a gate electrode of the first transistor 1001.

Next, the method for driving the light emitting device will be describedbelow. FIG. 6 is a diagram explaining an operation of a frame with time.In FIG. 6, a horizontal direction indicates time passage while alongitudinal direction indicates the number of scanning stages of a gatesignal line.

When an image is displayed on the light emitting device of the presentinvention, a rewriting operation is carried out repeatedly during adisplaying period. The number of the rewriting operations is notparticularly limited. However, the rewriting operation is preferablyperformed about 60 times a second such that a person who watches adisplayed image does not detect flicker in the image. A period ofoperating the rewriting operation and the displaying operation of oneimage (one frame) is, herein, referred to as one frame period.

As shown in FIG. 6, one frame is divided into four sub-frames 501, 502,503 and 504 including writing periods 501 a, 502 a, 503 a and 504 a andholding periods 501 b, 502 b, 503 b and 504 b. The light emittingelement applied with a signal for emitting light emits light during theholding periods. The length ratio of the holding periods in the firstsub-frame 501, the second sub-frame 502, the third sub-frame 503 and thefourth sub-frame 504 satisfies 2³: 2²: 2¹: 2⁰=8:4:2:1. This allows thelight emitting device to exhibit 4-bit gray scale. Further, the numberof bits and the number of gray scales are not limited to those as shownin this embodiment mode. For instance, one frame may be divided intoeight sub-frames so as to achieve 8-bit gray scale.

The operation in one frame will be described. In the sub-frame 501, thewriting operation is first performed in a 1^(st) row to a last row,sequentially. Therefore, the starting time of the writing periods isvaried for each row. The holding period 501 b sequentially starts in therows in which the writing period 501 a has been terminated. In theholding period 501 b, a light emitting element applied with a signal foremitting light remains in a light emitting state. Upon terminating theholding period 501 b, the sub-frame 501 is changed to the next sub-frame502 sequentially in the rows. In the sub-frame 502, a writing operationis sequentially performed in the 1^(st) row to the last row in the samemanner as the sub-frame 501. The above-mentioned operations are carriedout repeatedly up to the holding period 504 b of the sub-frame 504 andthen terminated. After terminating the operation in the sub-frame 504,an operation in the next frame starts. Accordingly, the sum of thelight-emitting time in respective sub-frames corresponds to the lightemitting time of each light emitting element in one frame. By changingthe light emitting time for each light emitting element and combiningsuch the light emitting elements variously within one pixel, variousdisplay colors with different brightness and different chromaticity canbe obtained.

When the holding period is intended to be forcibly terminated in the rowin which the writing period has already been terminated and the holdingperiod has started prior to terminating the writing operation up to thelast row as shown in the sub frame 504, an erasing period 504 c ispreferably provided after the holding period 504 b so as to stop lightemission forcibly. The row where light emission is forcibly stopped doesnot emit light for a certain period (this period is referred to as a nonlight emitting period 504 d). Upon terminating the writing period in thelast row, a writing period of a next sub-frame (or, a next frame)immediately starts from a first row, sequentially. This can prevent thewriting period in the sub-frame 504 from overlapping with the writingperiod in the next sub-frame.

Although the sub-frames 501 to 504 are arranged in order of descendingthe length of the holding period in this embodiment mode, they are notnecessary to be arranged in this order. For example, the sub-frames maybe arranged in ascending order of the length of the holding period.Alternatively, the sub-frames may be arranged in random order. Inaddition, these sub-frames may further be divided into a plurality offrames. That is, scanning of gate signal lines may be performed atseveral times during a period of supplying same video signals.

The operations in the wiring period and the erasing period of thecircuits as shown in FIG. 4 will be described below.

The operation in the writing period will be described first. In thewriting period, the gate signal line 911 in the n-th row (n is a naturalnumber) is electrically connected to the writing gate signal line drivercircuit 913 via the switch 918. The gate signal line 911 in the n-th rowis electrically disconnected to the erasing gate signal line drivercircuit 914. The source signal line 912 is electrically connected to thesource signal line driver circuit 915 via the switch 920. In this case,a signal is input in a gate of the first transistor 901 connected to thegate signal line 911 in the n-th row (n is a natural number), therebyturning the first transistor 901 on. At this moment, video signals aresimultaneously input in the source signal lines in the first to lastcolumns. Further, the video signals input from the source signal line912 in each column are independent from one anther. The video signalsinput from the source signal line 912 are input in a gate electrode ofthe second transistor 902 via the first transistor 901 connected to therespective source signal lines. At this time, the amount of currentsupplied to the light emitting element 903 from the current supply line917 is decided by the signals input in the second transistor 902. Also,it is decided whether the light emitting element 903 emits light oremits no light depending on the amount of current. For instance, whenthe second transistor 902 is of a P-channel type, the light emittingelement 903 emits light by inputting a low level signal in the gateelectrode of the second transistor 902. On the other hand, when thesecond transistor 902 is of an N-channel type, the light emittingelement 903 emits light by inputting a high level signal in the gateelectrode of the second transistor 902.

Next, the operation in the erasing period will be described. In theerasing period, the gate signal line 911 in the n-th row (n is a naturalnumber) is electrically connected to the erasing gate signal line drivercircuit 914 via the switch 919. The gate signal line 911 in the n-th rowis not electrically connected to the writing gate signal line drivercircuit 913. The source signal line 912 is electrically connected to thepower source 916 via the switch 920. In this case, upon inputting asignal in the gate of the first transistor 901, which is connected tothe gate signal line 911 in the n-th row, the first transistor 901 isturned on. At this time, erasing signals are simultaneously input in thefirst to last columns of the source signal lines. The erasing signalsinput from the source signal line 912 are input in the gate electrode ofthe second transistor 902 via the first transistor 901, which isconnected to each source signal line. A supply of current flowingthrough the light emitting element 903 from the current supply line 917is forcibly stopped by the signals input in the second transistor 902.This makes the light emitting element 903 emit no light forcibly. Forexample, when the second transistor 902 is of a P-channel type, thelight emitting element 903 emits no light by inputting a high levelsignal in the gate electrode of the second transistor 902. On the otherhand, when the second transistor 902 is of an N-channel type, the lightemitting element 903 emits no light by inputting a low level signal inthe gate electrode of the second transistor 902.

Further, in the erasing period, a signal for erasing is input in then-th row (n is a natural number) by the above-mentioned operation.However, as mentioned above, the n-th row sometimes remains in theerasing period while another row (e.g., an m-th row (m is a naturalnumber)) remains in the writing period. In this case, since a signal forerasing is necessary to be input in the n-th row and a signal forwriting is necessary to be input in the m-th row by utilizing the sourcesignal line in the same column, the after-mentioned operation ispreferably carried out.

After the light emitting element 903 in the n-th row becomes a non-lightemitting state by the above-described operation in the erasing period,the gate signal line 911 and the erasing gate signal line driver circuit914 are immediately disconnected to each other and the source signalline 912 is connected to the source signal line driver circuit 915 byturning the switch 920 on/off. The gate signal line 911 and the writinggate signal line driver circuit 913 are connected to each other whilethe source signal line and the source signal line driver circuit 915 areconnected to each other. A signal is selectively input in the signalline in the m-th row from the writing gate signal line driver circuit913 and the first transistor is turned on while signals for writing areinput in the source signal lines in the first to last columns from thesource signal line driver circuit 915. By inputting these signals, thelight emitting element in the m-th row emits light or no light.

After terminating the writing period in the m-th row as mentioned above,the erasing period immediately starts in the n+1-th row. Therefore, thegate signal line 911 and the writing gate signal line driver circuit 913are disconnected to each other while the source signal line is connectedto the power source 916 by turning the switch 920 on/off. Also, the gatesignal line 911 and the writing gate signal line driver circuit 913 aredisconnected to each other while the gate signal line 911 is connectedto the erasing gate signal line driver circuit 914. A signal isselectively input in the gate signal line in the n+1-th row from theerasing gate signal line driver circuit 914 to input a signal forturning on the first transistor in the first transistor while an erasingsignal is input therein from the power source 916. Upon terminating theerasing period in the n+1-th row in this manner, the writing periodimmediately starts in the m+1-th row. The erasing period and the writingperiod may be repeated alternately until the erasing period of the lastrow in the same manner.

Although the writing period in the m-th row is provided between theerasing period in the n^(th) row and the erasing period of the n+1-throw in this embodiment mode, the present invention is not limitedthereto. The writing period of the m-th row may be provided between theerasing period in the n−1-th row and the erasing period in the n-th row.

Furthermore, in this embodiment mode, when the non-light emitting period504 d is provided like the sub-frame 504, the operation of disconnectingthe erasing gate signal line driver circuit 914 from one gate signalline while connecting the writing gate signal line driver circuit 913 toother gate signal line is carried out repeatedly. This operation may beperformed in a frame in which a non-light emitting period is notparticularly provided.

Embodiment Mode 5

A circuit having a function of controlling light emission or non lightemission of a light emitting element is not limited to the one shown inFIG. 4. For example, a circuit as shown in FIG. 7 may be used.

In FIG. 7, a first transistor 2101, a second transistor 2103, an erasingdiode 2111, and a light emitting element 2104 are arranged. A source anda drain of the first transistor 2101 are independently connected to asignal line 2105 and a gate of the second transistor 2103. The gate ofthe first transistor 2101 is connected to a first gate line 2107. Asource and a drain of the second transistor 2103 are independentlyconnected to a power source line 2106 and the light emitting element2104. The erasing diode 2111 is connected to both the gate of the secondtransistor 2103 and a second gate line 2117.

A holding capacitor 2102 has a function of holding a gate potential ofthe second transistor 2103. Therefore, the holding capacitor connectedbetween the gate of the second transistor 2103 and the power source line2106. However, the position of the holding capacitor 2102 is not limitedthereto. The holding capacitor 2102 may be placed such that the holdingcapacitor holds the gate potential of the second transistor 2103. Whenthe gate potential of the second transistor 2103 can be held by using agate capacitor of the second transistor 2103 or the like, the holdingcapacitor 2102 may be eliminated.

A driving method is as follows. The first gate line 2107 is selected toturn the first transistor 2101 on, and then a signal is input in theholding capacitor 2102 from the signal line 2105. Then, a current of thesecond transistor 2103 is controlled in accordance with the signal sothat the current flows to a second power source line 2108 from a firstpower source line 2106 through the light emitting element 2104.

In order to erase the signal, the second gate line 2117 is selected (inthis case, a potential of the second gate line is increased) and theerasing diode 2111 is turned on to feed a current to a gate of thesecond transistor 2103 from the second gate line 2117. Consequently, thesecond transistor 2103 becomes an off-state. Then, a current does notflow to the second power source line 2108 from the first power sourcelimp 2106 through the light emitting element 2104. As a result, anon-light emitting period can be made and a lighting period can befreely controlled.

In order to hold a signal, the second gate line 2117 is not selected (inthis case, a potential of the second date line is reduced). Thus, sincethe erasing diode 2111 is turned off, a gate potential of the secondtransistor 2103 is held.

Further, the erasing diode 2111 is not particularly limited so long asit is an element having a rectifying property. Either a PN-type diode ora PIN-type diode may be used. Alternatively, either a Schottky diode ora zener diode may be used.

Further, a diode connection (i.e., a gate and a drain art connected toeach other) may be carded out using transistors. Moreover, a P-channeltype transistor may be used.

Embodiment Mode 6

Examples of light emitting device including light emitting elements ofthe present invention will be described referring to cross sectionalviews of FIGS. 8A to 8C.

In each of FIGS. 8A to 8C, a transistor 11 that is provided for drivinga light emitting element 12 of the present invention is surrounded by adashed line. The light, emitting element 12 of the present inventioncomprises a light emitting layer 15 between a first electrode 13 and asecond electrode 14. A drain of the transistor 11 and the firstelectrode 13 are electrically connected to each other via a wiring 17that passes through a first interlayer insulating film 16 (16 a, 16 band 16 c). The light emitting element 12 is isolated from other adjacentlight emitting element by a partition wall layer. A light emittingdevice having such a structure is provided over a substrate 10 in thisembodiment mode.

The transistor 11 shown in each of FIGS. 8A to 8C is of a top-gate typein which a gate electrode is provided on a semiconductor layer at a sideopposite to the substrate. Further, the structure of the transistor 11is not particularly limited thereto, and for example, a bottom-gate typestructure may be employed. In the case of the bottom-gate type, either astructure in which a protection film is formed over a semiconductorlayer forming a channel (a channel protection type) or a structure inwhich a semiconductor layer forming a channel is partly etched (achannel-etched type) may be used.

Furthermore, a semiconductor layer included in the transistor 11 may beformed using any one of a crystalline semiconductor, an amorphoussemiconductor a semiamorphous semiconductor, and the like.

Specifically, the semiamorphous semiconductor has an intermediatestructure between an amorphous structure and a crystalline structure(including a single crystal structure and a polycrystalline structure),and a third condition that is stable in term of free energy. Thesemiamorphous semiconductor further includes a crystalline region havinga short range order along with lattice distortion. A crystal grain witha size of 0.5 to 20 nm is included in at least a part of ansemiamorphous semiconductor film. Raman spectrum is shifted toward lowerwavenumbers than 520 cm⁻¹. The diffraction peaks of (111) and (220),which are believed to be derived from Si crystal lattice, are observedin the semiamorphous semiconductor by the X-ray diffraction. Thesemiamorphous semiconductor contains hydrogen or halogen of at least 1atom % or more for terminating dangling bonds. The semiamorphoussemiconductor is also referred to as a microcrystalline semiconductor.The semiamorphous semiconductor is formed by glow dischargedecomposition with silicide gas (plasma CVD). As for the silicide gas,SiH₄, Si₂H₆, SiH₂C₆, SIHCl₃, SiCl₄, SiF₄ and the like can be used. Thesilicide gas may also be diluted with H₂, or a mixture of H₂ and one ormore of rare gas elements selected from He, Ar, Kr and Ne. The dilutionratio is set to be in the range of 1:2 to 1:1,000. The pressure is setto be approximately in the range of 0.1 to 133 Pa. The power frequencyis set to be 1 to 120 MHz, and preferably, 13 to 60 MHz. A substrateheating temperature may be set to be 300° C. or less, and preferably,100 to 250° C. With respect to impurity elements contained in the film,each concentration of impurities for atmospheric constituents such asoxygen, nitrogen and carbon is preferably set to be 1×10²⁰/cm³ or less.In particular, the oxygen concentration is set to be 5×10¹⁹/cm³ or less,and preferably, 1×10¹⁹/cm³ or less.

As a specific example of a crystalline semiconductor layer asemiconductor layer made from single crystalline silicon,polycrystalline silicon, silicon germanium, or the like can be given.The crystalline semiconductor layer may be formed by lasercrystallization. For example, the crystalline semiconductor layer may beformed by crystallization with use of a solid phase growth method usingnickel or the like.

When a semiconductor layer is formed using an amorphous substance, e.g.,amorphous silicon, it is preferable to use a light emitting device withcircuits including only N-channel transistors as the transistor 11 andother transistor (a transistor included in a circuit for driving a lightemitting element). Alternatively, a light emitting device with circuitsincluding either N-channel transistors or P-channel transistors may beemployed. Also, a light emitting device with circuits including both anN-channel transistor and a P-channel transistor may be used.

The first interlayer insulating film 16 may include either plural layersas shown in FIGS. 8A and 8C or a single layer. Specifically, aninterlayer insulating layer 16 a is formed using an inorganic materialsuch as silicon oxide and silicon nitride. An interlayer insulatinglayer 16 b is formed using acrylic, siloxane (which is a compound thathas a skeleton structure formed by silicon (Si)-oxygen (O) bonds andincludes hydrogen or an organic group such as an alkyl group as itssubstituent), or a substance with a self-planarizing property that canbe formed by applying a material such as silicon oxide. An interlayerinsulating layer 16 c is formed using a silicon nitride film containingargon (Ar). The substances constituting the respective layers are notparticularly limited thereto. Therefore, substances other than theabove-mentioned substances may be employed. Alternatively, a layerformed using a substance other than the above mentioned substances maybe provided in combination with the above described layers. Accordingly,the first interlayer insulating film 16 may be formed by using both aninorganic material and an organic material or by using either aninorganic material or an organic material.

The edge portion of the partition wall layer 18 preferably has a shapein which the radius of curvature is continuously varied. This partitionwall layer 18 is formed by using acrylic, siloxane, resist, siliconoxide, or the like. Further, the partition wall layer 18 may be formedusing any one or both of an inorganic film and an organic film.

FIGS. 8A and 8C show the structures in which only the first interlayerinsulating film 16 (16 a, 16 b and 16 c) is sandwiched between thetransistors 11 and the light emitting elements 12. Alternatively, asshown in FIG. 8B, the first interlayer insulating film 16 (16 a and 16b) and a second interlayer insulting film 19 (19 a and 19 b) may beprovided between the transistor 11 and the light emitting element 12. Inthe light emitting device as shown in FIG. B, the first electrode 13passes through the second interlayer insulating film 19 to be connectedto the wiring 17.

The second interlayer insulating film 19 may include either plurallayers or a single layer as well as the first interlayer insulating film16. A second interlayer insulating layer 19 a is formed using acrylic,siloxane, or a substance with a self-planarizing property that can beformed by applying a material such as silicon oxide. A second interlayerinsulating layer 19 b is formed using a silicon nitride film containingargon (Ar). The substances constituting the respective layers of thesecond interlayer insulating film are not particularly limited thereto.Therefore, substances other than the above-mentioned substances may beemployed. Alternatively, a layer made from a substance other than theabove-mentioned substances may be provided in combination with thelayers 19 a and 19 b. Accordingly, the second interlayer insulating film39 may be formed by using both an inorganic material and an organicmaterial or by using either an inorganic material or an organicmaterial.

When the first electrode and the second electrode are both formed usinga substance with a light transmitting property in the light emittingelement 12, light generated in the light emitting element can be emittedthrough both the first electrode 13 and the second electrode 14 as shownin arrows in FIG. 8A. When only the second electrode 14 is formed usinga substance with a light transmitting property, light generated in thelight emitting element 12 can be emitted only through the secondelectrode 14 as shown in an arrow of FIG. 8B. In this case, the firstelectrode 13 is preferably formed using a material with highreflectance. Alternatively, a film (reflection film) formed using amaterial with high reflectance is preferably provided underneath thefirst electrode 13. When only the first electrode 13 is formed using asubstance with a light transmitting property, light generated in thelight emitting element 12 can be emitted only through the firstelectrode 13 as shown in an snow of FIG. 8C. In this case, the secondelectrode 14 is preferably formed using a material with high reflectanceor a reflection film is preferably provided over the second electrode14.

Moreover, in the light emitting element 12, the first electrode 13 mayserves as an anode and the second electrode 14 may serve as a cathode.Alternatively, the first electrode 13 may serves as a cathode and thesecond electrode 14 may serves as an anode. In the former case, thetransistor 11 is a P-channel transistor. In the latter case, thetransistor 11 is an N-channel transistor.

Embodiment Mode 7

As described in Embodiment Modes 4 to 6, a light emitting element of thepresent invention may be connected to a transistor to be used as a pixelof an active matrix light emitting device which emits light or no lightupon receiving a signal from the transistor. Alternatively, a lightemitting element of the present invention may be used for a passivelight emitting device as shown in FIG. 46 that drives the light emittingelement without providing an element for driving the transistor and thelike.

FIG. 46 shows a perspective view of a passive light emitting devicemanufactured using the present invention. In FIG. 46, an electrode 1902and an electrode 1906 are provided between a substrate 1901 and asubstrate 1907. The electrode 1902 and the electrode 1906 are providedto intersect each other. Further, a light emitting layer 1905 (which isdepicted by a dashed line such that the arrangement of the electrode1902, a partition wall layer 1904 and the like can be recognized) isprovided between the electrode 1902 and the electrode 1906. In addition,a hole transporting layer, an electron transporting layer and the likemay be provided between the light emitting layer 1905 and the electrode1902, or between the light emitting layer 1905 and the electrode 1906.The partition wall layer 1904 is provided at the edge of the electrode1902. Thus, the edge of the electrode 1902 is covered with the partitionwall layer 1904. Furthermore, the passive light emitting device can bedriven at low power consumption by using a light emitting element of thepresent invention that is operated at a low driving voltage.

Embodiment Mode 8

By mounting a light emitting device of the present invention, anelectronic appliance that can display favorable images for a long timeand has less false recognition of information due to fluctuation of adisplay image, can be obtained.

Examples of electronic appliances on which light emitting device of thepresent invention is mounted will be shown in FIGS. 9A to 9C.

FIG. 9A shows a laptop personal computer manufactured in accordance withthe present invention, comprising a main body 5521, a housing 5522, adisplay portion 5523, a keyboard 5524, and the like. By incorporating alight emitting device having a light emitting element of the presentinvention into the display portion, the personal computer can becompleted.

FIG. 9B shows a portable phone manufactured in accordance with thepresent invention, comprising a main body 5552, a display portion 5551,an audio output portion 5554, an audio input portion 5555, operationswitches 5556 and 5557, an antenna 5553 and the like. By incorporating alight emitting device having a light emitting element of the presentinvention into the display portion, the portable phone can be completed.

FIG. 9C shows a television receiver manufactured in accordance with thepresent invention, comprising a display portion 5531, a housing 5532,speakers 5533, and the like. By incorporating a light emitting devicehaving a light emitting element of the present invention into thedisplay portion, the television receiver can be completed.

As set forth above, a light emitting device of the present invention issuitable to be used as a display portion of various kinds of electronicappliances.

Although the laptop personal computer, the portable phone and thetelevision receiver are described in the present embodiment mode, lightemitting devices having light emitting elements of the present inventionmay be mounted on a car navigation, a camera, a lighting apparatus andthe like.

Embodiment 1 Synthetic Example 1

A method for synthesizing an anthracene derivative represented by thestructural formula (1) will be described in this synthetic example.

[Step 1]

A method for synthesizing 9,10-bis(4-bromophenyl)-2-tert-butylanthracene will be described.

Under nitrogen gas stream at a temperature of −78° C., 1.58 mol/L (13.4ml) of a butyllithium hexane solution was dropped in a dry ethersolution (200 ml) containing 5.0 g of 1,4-dibromobenzene. After drippingthe butyllithium hexane solution, the mixture was stirred for one hourat the same temperature. At a temperature of −78° C., a dry ethersolution (40 ml) containing 2-tert-butyl anthraquinone (2.80 g) wasdropped in the mixture, and then the reaction solution was slowly heatedto a room temperature. After the reaction solution was stirred forovernight, water was added thereto, and an organic layer was extractedwith ethyl acetate. The organic layer was washed with saturated salineand dried with magnesium sulfate. The dried matter was filtered andconcentrated. Then, the residue was purified by a silica gelchromatography (a developing solvent, hexane-ethyl acetate) to obtain5.5 g of a compound.

When the thus obtained compound was measured by a nuclear magneticresonance (¹H-NMR) method, it was confirmed that the compound was 9,10-bis(4-bromophenyl)-2-tert-butyl-9,10-dihydroxy-9,10-dihydroanthracene.

The ¹H-NMR of this compound is shown below. The ¹H-NMR (300 MHz, CDCl₃):δ=1.31 (s, 9H), 2.81 (s, 1H), 2.86 (s, 1H), 6.82-6.86 (m, 4H), 7.13-7.16(m, 4H), 7.36-7.43 (m, 3H), and 7.53-7.70 (m, 4H).

Also, a synthetic scheme (b-1) of the 9,10-bis(4-bromophenyl)-2-tert-butyl-9,10-dihydroxy-9,10-dihydroanthraceneis shown below.

Under atmospheric air, 987 mg (1.55 mmol) of the thus obtained9,10-bis(4-bromophenyl)-2-tert-butyl-9,10-dihydroxy-9,10-dihydroanthracene,664 mg (4 mmol) of potassium iodide and 1.48 g (14 mmol) of sodiumphosphine acid monohydrate were suspended in 12 ml of glacial aceticacid. The mixture was refluxed and stirred while heating for two hours.The reaction mixture was cooled to the room temperature and the thusgenerated precipitate was filtered and washed with about 50 ml ofmethanol to obtain a filtrate. The filtrate was dried to obtain 700 mgof a compound which was a cream-colored powder. The yield was 82%. Whenthis compound was measured by a nuclear magnetic resonance (¹H-NMR,¹³C-NMR) method, it was confirmed that the compound was 9,10-bis(4-bromophenyl)-2-tert-butylanthracene.

The ¹H-NMR and the ¹³C-NMR of this compound are shown below.

The ¹H-NMR (300 MHz, CDCl₃): δ=1.28 (s, 9H), 7.25-7.37 (m, 6H),7.44-7.48 (m, 1H), 7.56-7.65 (m, 4H), and 7.71-7.76 (m, 4H).

The ¹³C-NMR (47 MHz, CDCl₃): δ=30.8, 35.0, 120.8, 121.7, 121.7, 124.9,125.0, 125.2, 126.4, 126.6, 126.6, 128.3, 129.4, 129.7, 129.9, 131.6,131.6, 133.0, 133.0, 135.5, 135.7, 138.0, 138.1, and 147.8.

Further, a synthetic scheme (b-2) of 9,10-bis(4-bromophenyl)-2-tert-butylanthracene is shown below.

[Step 2]

A method for synthesizing 3-(N-phenylamino)-9-phenylcarbazole will bedescribed.

Firstly, 243 g (100 mmol) of N-phenylcarbazole was dissolved in 600 mlof glacial acetic acid, and 17.8 g (100 mmol) of N-bromo succinic acidimide was slowly added thereto. The mixture was stirred for overnight ata room temperature. This glacial acetic acid solution was dropped in 1 Lof ice water while stirring them. A precipitated white solid was washedthree times with water. This white solid was dissolved in 150 ml ofdiethyl other, and washed with a saturated sodium hydrogencarbonatesolution and water. This organic layer was dried with magnesium sulfate,and filtered. The obtained filtrate was concentrated. The thus obtainedresidue was added with about 50 ml of methanol and uniformly dissolvedtherein by being irradiated with supersonic. This solution was left toprecipitate a white solid. This solution was filtrated and the filtratewas dried to obtain 28.4 g (the yield: 88%) of3-bromo-9-phenylcarbazole, which was a white powder.

Further, a synthetic scheme (c-1) of 3-bromo-9-phenylcarbazole is shownbelow.

Next, under nitrogen, 110 ml of dehydrated xylene and 7.0 g (75 mmol) ofaniline were added to a mixture of 19 g (60 mmol) of3-bromo-9-phenylcarbazole, 340 mg (0.6 mmol) of bis(dibenzylideneacetone) palladium (0) (abbreviation: Pd(dba)₂), 1.6 g (3.0 mmol) of1,1-bis(diphenylphosphino) ferrocene (abbreviation: DPPF), and 13 g (180mmol) of sodium-tert-butoxide (abbreviation: tBuONa). This mixture wasstirred while heating under nitrogen atmosphere at 90° C. for 7.5 hours.After the termination of the reaction, about 500 ml of toluene, whichwas heated to 50° C., was added to the suspension and this suspensionwas filtered through florisil, alumina and celite. The thus obtainedfiltrate was concentrated and the residue was added with hexane-ethylacetate and irradiated with supersonic. The thus obtained suspension wasfiltered and the filtrate was dried to obtain 15 g (the yield: 75%) of acream-colored powder. By using a nuclear magnetic resonance (¹H-NMR)method, it was confirmed that this cream-colored powder was3-(N-phenylamino)-9-phenylcarbazole (abbreviation: PCA).

The ¹H-NMR of the compound is shown below. The ¹H-NMR charts are alsoshown in FIGS. 13A and 13B. Further, FIG. 13B is a chart showing anenlarged part in the range of 5 ppm to 9 ppm of FIG. 13A.

The ¹H-NMR (300 MHz, CDCl₃): δ=5.69 (s, 1H), 6.84 (t, J=6.9, 2 H), 6.97(d, J=7.8, 2H), 7.20-7.61 (m, 13H), 7.90 (s, 1H), and 8.04 (d, j=7.8,1H).

Further, a synthetic scheme (c-2) of 3-(N-phenylamino)-9-phenylcarbazoleis shown below.

[Step 3]

A method for synthesizing 9,10-bis{4-[N-(9-phenylcarbazole-3-yl)-N-phenylamino]phenyl}-2-tert-butylanthracene (abbreviation. PCABPA) will be described.

Under nitrogen, 10 ml of dehydrated toluene was added to a mixture of540 mg (1.0 mmol) of 9, 10-bis(4-bromophenyl)-2-tert-butylanthracene,670 mg (2.0 mmol) of 3-(N-phenylamino)-9-phenylcarbazole, 12 mg (0.02mmol) of bis(dibenzylidene acetone) palladium (0), 110 mg (0.2 mmol) of1,1-bis(diphenylphosphino) ferrocene, and 600 mg (6.2 mmol) ofsodium-tert-butoxide. This mixture was stirred while heating at 90° C.for five hours under nitrogen atmosphere. After termination of thereaction, the suspension was added with about 100 ml of toluene, andthen filtered through florisil, alumina and celite. The thus obtainedfiltrate was concentrated and a target matter was obtained by a silicagel chromatography (toluene:hexane=1:1). The target matter wasconcentrated and the thus obtained residue was recrystallized bydiclomethane-hexane to obtain 500 mg (the yield 48%) of a yellow greenpowder. By using a nuclear magnetic resonance (¹H-NMR) method, it wasconfirmed that this yellow green powder was 9,10-bis{4-[N-(9-phenylcarbazole-3-yl)-N-phenylamino]phenyl}-2-tert-butylanthracene(abbreviation: PCABPA).

The ¹H-NMR of the compound is shown below. The ¹H-NMR charts are alsoshown in FIGS. 14A and 14B. Further, FIG. 14B is a chart showing anenlarged part in the range of 65 ppm to 85 ppm of FIG. 14A.

The ¹H-NMR (300 MHz, DMSO-d): δ=3.33 (s, 9H), 6.98-7.79 (m, 44H), and8.16-8.27 (m, 4H).

Further, a synthetic scheme (d-1) of PCABPA is shown below.

The absorption spectrums of the PCABPA are shown in FIG. 10. In FIG. 10,a horizontal axis represents a wavelength (nm) and a longitudinal axisrepresents the absorption intensity (given unit). Further, a line (a)indicates the absorption spectrum in the case where the PCABPA was afilm form whereas a line (b) indicates the absorption spectrum in thecase where the PCABPA was dissolved in a toluene solution. The lightemission spectrum of the PCABPA is shown in FIG. 11. In FIG. 11, ahorizontal axis represents a wavelength (nm) and a longitudinal axisrepresents the light emission intensity (given unit). A line (a)indicates the light emission spectrum (an excited wavelength: 352 nm) inthe case where the PCABPA was a film form and a line (b) indicates thelight emission spectrum (an excited wavelength: 390 nm) in the casewhere the PCABPA was dissolved in a toluene solution. According to FIG.11, it is known that light emission from the PCABPA has a peak at 488 nmin the film form state and has a peak at 472 nm in the dissolved statein the toluene solution. These light emissions were recognized as bluelight emissions.

When a film was formed by evaporation of the thus obtained PCABPA and anionization potential of the compound in the thin film state was measuredby using a photoelectron spectrometer (#AC-2, Riken Keiki Co., Ltd.),the ionization potential was 5.31 eV. An absorption spectrum of thecompound in the thin film state was measured by using an UV and visiblelight spectrophotometer (#V-550, Japan Spectroscopy Corporation), and awavelength of an absorption edge at a longer wavelength side of theabsorption spectrum was set to be an energy gap (2.77 eV). Under theseconditions, when the LUMO level was measured, it was −2.54 eV.

Further, when a decomposition temperature T_(d) of the thus obtainedPCABPA was measured by a thermo-gravimetric/differential thermalanalyzer (#TG/DTA 320, Seiko Instruments Inc., the T_(d) was 485° C.,and therefore, it was known that the PCABPA showed an excellent heatresistant property.

In addition, an oxidation reaction characteristic and a reductionreaction characteristic of the PCABPA were measured by a cyclicvoltammetry (CV) measurement. Further, an electrochemical analyzer (#ALSmodel 600A, BAS Inc.) was used for the measurement.

In relation to a solution used in the CV measurement, dehydrateddimethylformamide (DMF) was used as a solvent.Tetraperchlorate-n-butylammonium (n-Bu₄NClO₄), which was a supportingelectrolyte, was dissolved in the solvent such that the concentration ofthe tetraperchlorate-n-butylammonium was 100 mmol/L. Also, the PCABPA,which was an object to be measured, was dissolved such that theconcentration thereof was set to be 1 mmol/L. Further, a platinumelectrode (a PTE platinum electrode, BAS Inc.) was used as a workelectrode. A platinum electrode (a VC-3 Pt counter electrode (5 cm), BASInc.) was used as an auxiliary electrode. An Ag/Ag+ electrode (an RBE 5nonaqueous reference electrode, BAS Inc.) was used as a referenceelectrode.

The oxidation reaction characteristic was measured as follows. After apotential of the work electrode with respect to the reference electrodewas changed to 0.6 V from −0.01 V, a scan for changing the potential to−0.01 V from 0.6 V was set as one cycle, and 100 cycle measurements werecarried out. Further, the scanning speed of the CV measurement was setto be 0.1 V/s.

The reduction reaction characteristic was measured as follows. After apotential of the work electrode with respect to the reference electrodewas changed to −2.7 V from −0.9 V, a scan for changing the potential to−0.9 V from −2.7 V was set as one cycle, and 100 cycle measurements werecarried out. Further the scanning speed of the CV measurement was set tobe 0.1 V/s.

Results of measuring the oxidation reaction characteristic of the PCABPAare shown in FIG. 12A. Also, results of measuring the reduction reactioncharacteristic of the PCABPA are shown in FIG. 12B. In each of FIGS. 12Aand 12B, a horizontal axis represents a potential (V) of the workelectrode with respect to the reference electrode, while a longitudinalaxis represents an amount of current flowing between the work electrodeand the auxiliary electrode (1×10⁻⁵ A).

According to FIG. 12A, it was known that an oxidation potential was 0.42V (vs. Ag/Ag electrode). According to FIG. 12B, it was known that areduction potential was −2.39 V (vs. Ag/Ag electrode). Although the scanwas repeated 100 times, a peak position and a peak intensity of a CVcurve were hardly changed in each of the oxidation reaction and thereduction reaction. Thus, it was known that the PCABPA, which was one ofcompounds of the present invention, was absolutely stable with respectto the repetition of the oxidation reaction. In addition, it was alsoknown that the PCABPA was absolutely stable with respect to therepetition of the reduction reaction.

Synthetic Example 2

A method for synthesizing 9,10-bis{4′-[N-(9-phenylcarbazole-3-yl)-N-phenylamino]biphenyl-4-yl}-2-tert-butylanthracene (abbreviation: PCABBA), which isan anthracene derivative represented by the structural formula (13),will be described in Synthetic Example 2.

[Step 1]

Firstly, a method for synthesizing 9,10-bis(4′-bromobiphenyl-1-yl)-2-tert-butylanthracene will be described.

Specifically, 655 g (21.0 mmol) of 4,4′-dibromobiphenyl was poured in athree-neck flask (500 ml), and nitrogen was substituted for air in thethree-neck flask. Next, 200 ml of tetrahydrofuran was added thereto. Themixture was cooled to −80° C., and then 145 ml (22.3 mmol) ofn-butyllithium (1.54 mol/L of a hexane solution) was dropped therein andthe mixture was stirred for one hour while keeping the temperature at−80° C. While still keeping the temperature at −80° C., a mixedsolution, in which 2.07 g (10.0 mmol) of anthraquinone was suspended in20 ml of tetrahydrofuran (abbreviation: THP), was dropped in thereaction solution. After the termination of the dropping, the mixturewas further stirred for two hours while the temperature was increased tothe room temperature from −80° C. After the reaction, 110 ml of ethanolwas added to the product and then stirred. Subsequently, the reactionsolution was washed with water and saturated saline, and then, driedwith magnesium sulfate. The reaction mixture was naturally filtered andthe filtrate was concentrated to obtain a light yellow solid (asynthetic scheme (e-1)).

The thus obtained light yellow solid, 6.64 g (40 mmol) of potassiumiodide, 12.7 g (120 mmol) of sodium phosphine acid monohydrate, and 120ml of glacial acetic acid were poured in an eggplant-type flask, whichwas a container with a volume capacity of 500 ml. The mixture wererefluxed for two hours. After the reaction, a temperature of the productwas cooled to the room temperature, and then, the precipitated solid wascollected by suction filtration. The solid was recrystallized fromdichloromethane-ethanol to obtain 3.43 g (the yield: 51%) of a lightyellow solid of 9, 10-bis(4′-bromobiphenyl-4-yl)-2-tert-butylanthracene,which was an object matter (a synthetic scheme (e-2)).

Further the synthetic schemes (e-1) and (e-2) of the Step 1 are shownbelow.

[Step 2]

Next, a method for synthesizing 9,10-bis{4′-[N-(9-phenylcarbazole-3-yl)-N-phenylamino]biphenyl-4-yl}-2-tert-butylanthracene, which is represented by thestructural formula (13) will be described.

Specifically, 700 mg (1.0 mmol) of the 9,10-bis(4′-bromobiphenyl-4-yl)-2-tert-butylanthracene, which was obtainedin the Step 1 of Synthetic Example 2, 670 mg (2.0 mmol) of the3-(N-phenylamino)-9-phenylcarbazole (abbreviation: PCA), which wasobtained in the Step 2 of Synthetic Example 1, 60 mg (0.10 mmol) ofbis(dibenzylideneacetone) palladium (0), 1.0 ml (050 mmol) oftri-tert-butylphosphine (a 10 wt % hexane solution), and 0.4 g (4.0mmol) of sodium-tert-butoxide were poured in a flask, 10 ml ofdehydrated xylene was added thereto, and nitrogen was substituted forair in the flask. The mixture was stirred while heating at 120° C. forsix hours under nitrogen atmosphere. After the reaction, about 200 ml oftoluene was added to the suspension. The mixture was filtered throughflorisil and celite. The thus obtained filtrate was concentrated and atarget matter was obtained by a silica gel chromatography(toluene:hexane=1:1). The target matter was concentrated and the thusobtained residue was recrystallized by being irradiated with supersonicto obtain 70 mg (the yield: 6%) of a beige powder of 9,10-bis{4′-[N-(9-phenylcarbazole-3-yl)-N-phenylamino]biphenyl-4-yl}-2-tert-butylanthracene (abbreviation: PCABBA), which wasa target matter.

Also, a synthetic scheme (f-1) of the Step 2 is shown below.

Results of a ¹H-NM analysis are shown below. Also, ¹H-NMR charts areshown in FIGS. 47A and 47B. Further, FIG. 47B is a chart showing anenlarged portion in the range of 9 ppm to 6 ppm of FIG. 47A.

The ¹H-NMR (300 MHz, DMSO-d): δ=1.22 (s, 9H), 7.04 (t, J=6.9 Hz, 2H),7.14-7.79 (m, 39H), 7.88-7.94 (m, 4H), 8.12 (d, J=1.5 Hz, 2H), and 8.20(d, J=8.4 Hz, 2H).

Further, an absorption spectrum of the PCABBA in a toluene solution isshown in FIG. 48. In FIG. 48, a horizontal axis represents a wavelength(n) and a longitudinal axis represents absorption intensity (givenunit). Also, a light emission spectrum of the PCABBA in a toluenesolution is shown in FIG. 49. In FIG. 49, a horizontal axis represents awavelength (nm) and a longitudinal axis represents light emissionintensity (given unit). According to FIG. 49, it was known that thelight emission of the PCABBA had a peak at 445 nm in the toluenesolution, and it was recognized that the light emission was blue.Therefore, it was known that the PCABBA was a suitable substance as alight emitting substance emitting blue light.

Embodiment 2

A method for manufacturing a light emitting element that uses the PCABPAsynthesized in Synthetic Example 1 as a light emitting substance and anoperational characteristic of the light emitting element will bedescribed in this embodiment.

As shown in FIG. 15, indium tin oxide containing silicon oxide wasformed over a glass substrate 301 by sputtering to form a firstelectrode 302. The thickness of the first electrode 302 was set to be110 nm. Further the first electrode was formed to have a square shapehaving the size of 2 mm×2 mm.

Next, the glass substrate 301 over which the first electrode 302 wasformed was fixed to a holder provided in a vacuum evaporation apparatus.

The inside of the vacuum evaporation apparatus was evacuated so that thepressure was reduced to 1×10⁻⁴ Pa. Then, a first layer 303 includingcopper phthalocyanine was formed on the first electrode 302 byevaporation. The thickness of the first layer 303 was set to be 20 nm.The first layer 303 serves as a hole injecting layer when the lightemitting element is operated.

Subsequently, a second layer 304 including NPB was formed on the firstlayer 303 by evaporation. The thickness of the second layer 304 was setto be 40 nm. The second layer 304 serves as a hole transporting layerwhen the light emitting element is operated.

A third layer 305 including t-BuDNA and PCABPA was formed on the secondlayer 304 by co-evaporation. The thickness of the third layer 305 wasset to be 40 nm. The mass ratio between t-BuDNA and PCABPA was adjustedto be 1:0.05. Thus, the PCABPA was dispersed in the t-BuDNA. The thirdlayer 305 serves as a light emitting layer when the light emittingelement is operated. Further the PCABPA serves as a light emittingsubstance.

Next, a fourth layer 306 including Alq₃ was formed on the third layer305 by evaporation. The thickness of the fourth layer 306 was set to be20 nm. The fourth layer 306 serves as an electron transporting layerwhen the light emitting element is operated.

A fifth layer 307 including calcium fluoride was formed on the fourthlayer 306 by evaporation. The thickness of the fifth layer 307 was setto be 1 nm. The fifth layer 307 serves as an electron injecting layerwhen the light emitting element is operated.

Next, a second electrode 308 including aluminum was formed on the fifthlayer 307. The thickness of the second electrode 308 was set to be 200nm.

When the voltage is applied to the light emitting element manufacturedabove such that a potential of the first electrode 302 is higher thanthat of the second electrode 308, current flows through the lightemitting element. Holes and electrons are recombined at the third layer305 serving as a light emitting layer to generate excited energy. Theexcited PCABPA emits light upon returning to a ground state.

This light emitting element was sealed in a glove box under nitrogenatmosphere so as not to expose the light emitting element to theatmospheric air. Thereafter, an operational characteristic of the lightemitting element was measured. Further, the measurement was carried outat room temperature (under an atmosphere where a temperature wasmaintained at 25° C.).

Measurement results are shown in FIG. 16 and FIG. 17. FIG. 16 shows ameasurement result of a voltage-luminance characteristic whereas FIG. 17shows a measurement result of a luminance-current efficiencycharacteristic. In FIG. 16, a horizontal axis represents the voltage (V)and a longitudinal axis represents the luminance (cd/m²). Also, in FIG.17, a horizontal axis represents the luminance (cd/m²) and alongitudinal axis represents the current efficiency (cd/A).

The light emission spectrum of the light emitting element manufacturedin this embodiment is shown in FIG. 18. In FIG. 18, a horizontal axisrepresents a wavelength (nm) and a longitudinal axis represents theintensity (given unit). According to FIG. 18, it was known that thelight emitting element of the present embodiment had a peak of lightemission spectrum at 477 nm, and emitted blue light. Moreover, the CIEchromaticity coordinates were x=0.16, y=0.28. As a consequence, it wasknown that the light emitting element of the present embodiment emittedblue light with good color purity.

Embodiment 3

A method for manufacturing a light emitting element that uses the PCABPAsynthesized in Synthetic Example 1 as a light emitting substance and anoperational characteristic of the light emitting element will bedescribed in this embodiment. Further, a light emitting element of thepresent embodiment is similar to the light emitting element ofEmbodiment 2 in a point of having a structure in which five layers arelaminated between a first electrode and a second electrode, whereinsubstances and thicknesses of these layers are different from oneanther. The present embodiment will be described with reference to FIG.15 also used in the description of Embodiment 2.

As shown in FIG. 15, indium tin oxide containing silicon oxide wasformed over a glass substrate 301 by sputtering to form a firstelectrode 302. The thickness of the first electrode 302 was set to be110 nm. Further the first electrode was formed to have a square shapehaving the size of 2 mm×2 mm.

Next, the glass substrate 301 over which the first electrode 302 wasformed was fixed to a holder provided in a vacuum evaporation apparatus.

The inside of the vacuum evaporation apparatus was evacuated so that thepressure was reduced to 1×10⁻⁴ Pa. Then, a first layer 303 includingcopper phthalocyanine was formed on the first electrode 302 byevaporation. The thickness of the first layer 303 was set to be 20 nm.The first layer 303 serves as a hole injecting layer when the lightemitting element is operated.

Subsequently, a second layer 304 including4,4′-bis[N-(4-biphenylyl)-N-phenylamino] biphenyl (abbreviation: BBPB)was formed on the first layer 303 by evaporation. The thickness of thesecond layer 304 was set to be 40 nm. The second layer 304 serves as ahole transporting layer when the light emitting element is operated.

A third layer 305 including t-BuDNA and PCABPA was formed on the secondlayer 304 by co-evaporation. The thickness of the third layer 305 wasset to be 40 nm. The mass ratio between t-BuDNA and PCABPA was adjustedto be 1:0.05. Thus, the PCABPA was dispersed in the t-BuDNA. The thirdlayer 305 serves as a light emitting layer when the light emittingelement is operated. Further, the PCABPA serves as a light emittingsubstance.

Next, a fourth layer 306 including Alq₃ was formed on the third layer305 by evaporation. The thickness of the fourth layer 306 was set to be20 nm. The fourth layer 306 serves as an electron transporting layerwhen the light emitting element is operated.

A fifth layer 307 including calcium fluoride was formed on the fourthlayer 306 by evaporation. The thickness of the fifth layer 307 was setto be 1 nm. The fifth layer 307 serves as an electron injecting layerwhen the light emitting element is operated.

Next, a second electrode 308 including aluminum was formed on the fifthlayer 307. The thickness of the second electrode 308 was set to be 200nm.

When the voltage is applied to the light emitting element manufacturedabove such that a potential of the first electrode 302 is higher thanthat of the second electrode 308, current flows through the lightemitting element. Holes and electrons are recombined at the third layer305 serving as a light emitting layer to generate excited energy. Theexcited PCABPA emits light upon returning to a ground state.

This light emitting element was sealed in a glove box under nitrogenatmosphere so as not to expose the light emitting element to theatmospheric air. Thereafter, an operational characteristic of the lightemitting element was measured. Further, the measurement was carried outat room temperature (under an atmosphere where a temperature wasmaintained at 25° C.).

Measurement results are shown in FIG. 19 and FIG. 20. FIG. 19 shows ameasurement result of a voltage-luminance characteristic whereas FIG. 20shows a measurement result of a luminance-current efficiencycharacteristic. In FIG. 19, a horizontal axis represents the voltage (V)and a longitudinal axis represents the luminance (cd/m²). Also, in FIG.20, a horizontal axis represents the luminance (cd/m²) and alongitudinal axis represents the current efficiency (cd/A).

The light emission spectrum of the light emitting element manufacturedin this embodiment is shown in FIG. 21. In FIG. 21, a horizontal axisrepresents a wavelength (nm) and a longitudinal axis represents theintensity (given unit). According to FIG. 21, it was known that thelight emitting element of the present embodiment had a peak of lightemission spectrum at 479 nm, and emitted blue light. Moreover, the CIEchromaticity coordinates were x=0.16, y=0.29. As a consequence, it wasknown that the light emitting element of the present embodiment emitsblue light with good color purity.

Embodiment 4

A method for manufacturing a light emitting element that uses the PCABPAsynthesized in Synthetic Example 1 as a light emitting substance and anoperational characteristic of the light emitting element will bedescribed in this embodiment. Further, a light emitting element of thepresent embodiment is similar to the light emitting element ofEmbodiment 2 in a point of having a structure in which five layers arelaminated between a first electrode and a second electrode, whereinsubstances and thicknesses of these layers are different from oneanther. The present embodiment will be described with reference to FIG.15 also used in the description of Embodiment 2.

As shown in FIG. 15, indium tin oxide containing silicon oxide wasformed over a glass substrate 301 by sputtering to form a firstelectrode 302. The thickness of the first electrode 302 was set to be110 nm. Further, the first electrode was formed to have a square shapehaving the size of 2 mm×2 mm.

Next, the glass substrate 301 over which the first electrode 302 wasformed was flied to a holder provided in a vacuum evaporation apparatus.

The inside of the vacuum evaporation apparatus was evacuated so that thepressure was reduced to 1×10⁻⁴ Pa. Then, a first layer 303 includingcopper phthalocyanine was formed on the first electrode 302 byevaporation. The thickness of the first layer 303 was set to be 20 nm.The first layer 303 serves as a hole injecting layer when the lightemitting element is operated.

Subsequently, a second layer 304 including BSPB was formed on the firstlayer 303 by evaporation. The thickness of the second layer 304 was setto be 40 nm. The second layer 304 serves as a hole transporting layerwhen the light emitting element is operated.

A third layer 305 including t-BuDNA and PCABPA was formed on the secondlayer 304 by co-evaporation. The thickness of the third layer 305 wasset to be 40 nm. The mass ratio between t-BuDNA and PCABPA was adjustedto be 1:0.1. Thus, the PCABPA was dispersed in the t-BuDNA. The thirdlayer 305 serves as a light emitting layer when the light emittingelement is operated. Further, the PCABPA serves as a light emittingsubstance.

Next, a fourth layer 306 including Alq₃ was formed an the third layer305 by evaporation. The thickness of the fourth layer 306 was set to be20 nm. The fourth layer 306 serves as an electron transporting layerwhen the light emitting element is operated.

A fifth layer 307 including calcium fluoride was formed on the fourthlayer 306 by evaporation. The thickness of the fifth layer 307 was setto be 1 nm. The fifth layer 307 serves as an electron injecting layerwhen the light emitting element is operated.

Next, a second electrode 308 including aluminum was formed on the fifthlayer 307. The thickness of the second electrode 308 was set to be 200nm.

When the voltage is applied to the light emitting element manufacturedabove such that a potential of the first electrode 302 is higher thanthat of the second electrode 308, current flows through the lightemitting element. Holes and electrons are recombined at the third layer305 serving as a light emitting layer to generate excited energy. Theexcited PCABPA emits light upon returning to a ground state.

This light emitting element was sealed in a glove box under nitrogenatmosphere so as not to expose the light emitting element to theatmospheric air. Thereafter, an operational characteristic of the lightemitting element was measured. Further the measurement was carried outat a room temperature (under an atmosphere where a temperature wasmaintained at 25° C.).

Measurement results are shown in FIG. 22 and FIG. 23. FIG. 22 shows ameasurement result of a voltage-luminance characteristic, whereas FIG.23 shows a measurement result of a luminance-current efficiencycharacteristic. In FIG. 22, a horizontal axis represents the voltage (V)and a longitudinal axis represents the luminance (cd/m²). Also, in FIG.23, a horizontal axis represents the luminance (cd/m²) and alongitudinal axis represents the current efficiency (cd/A).

The light emission spectrum of the light emitting element manufacturedin this embodiment is shown in FIG. 24. In FIG. 24, a horizontal axisrepresents a wavelength (nm) and a longitudinal axis represents theintensity (given unit). According to FIG. 24, it was known that thelight emitting element of the present embodiment had a peak of lightemission spectrum at 474 nm, and emitted blue light. Moreover, the CIEchromaticity coordinates were x=0.16, y=0.25. As a consequence, it wasknown that the light emitting element of the present embodiment emittedblue light with good color purity.

Embodiment 5

A method for manufacturing a light emitting element that uses the PCABPAsynthesized in Synthetic Example 1 as a light emitting substance and anoperational characteristic of the light emitting element will bedescribed in this embodiment. Further, a light emitting element of thepresent embodiment is similar to the light emitting element ofEmbodiment 2 in a point of having a structure in which five layers arelaminated between a first electrode and a second electrode, whereinsubstances and thicknesses of these layers are different from oneanther. The present embodiment will be described with reference to FIG.15 also used in the description of Embodiment 2.

As shown in FIG. 15, indium tin oxide containing silicon oxide wasformed over a glass substrate 301 by sputtering to form a firstelectrode 302. The thickness of the first electrode 302 was set to be110 nm. Further, the first electrode was formed to have a square shapehaving the size of 2 mm×2 mm.

Next, the glass substrate 301 over which the first electrode 302 wasformed was fixed to a holder provided in a vacuum evaporation apparatus.

The inside of the vacuum evaporation apparatus was evacuated so that thepressure was reduced to 1×10⁻⁴ Pa. Then, a first layer 303 includingDNTPD was formed on the first electrode 302 by evaporation. Thethickness of the first layer 303 was set to be 50 nm. The first layer303 serves as a hole injecting layer when the light emitting element isoperated.

Subsequently, a second layer 304 including NPB was formed on the firstlayer 303 by evaporation. The thickness of the second layer 304 was setto be 10 nm. The second layer 304 serves as a hole transporting layerwhen the light emitting element is operated.

A third layer 305 including CzPA and PCABPA was formed on the secondlayer 304 by co-evaporation. The thickness of the third layer 305 wasset to be 40 nm. The mass ratio between CzPA and PCABPA was adjusted tobe 1:0.05. Thus, the PCABPA was dispersed in the CzPA. The third layer305 serves as a light emitting layer when the light emitting element isoperated. Further the PCABPA serves as a light emitting substance.

Next, a fourth layer 306 including Alq₃ was formed on the third layer305 by evaporation. The thickness of the fourth layer 306 was set to be20 nm. The fourth layer 306 serves as an electron transporting layerwhen the light emitting element is operated.

A fifth layer 307 including calcium fluoride was formed on the fourthlayer 306 by evaporation. The thickness of the fifth layer 307 was setto be 1 nm. The fifth layer 307 serves as an electron injecting layerwhen the light emitting element is operated.

Next, a second electrode 308 including aluminum was formed on the fifthlayer 307. The thickness of the second electrode 308 was set to be 200nm.

When the voltage is applied to the light emitting element manufacturedabove such that a potential of the first electrode 302 is higher thanthat of the second electrode 308, current flows through the lightemitting element. Holes and electrons are recombined at the third layer305 serving as a light emitting layer to generate excited energy. Theexcited PCABPA emits light upon returning to a ground state.

This light emitting element was sealed in a glove box under nitrogenatmosphere so as not to expose the light emitting element to theatmospheric air. Thereafter, an operational characteristic of the lightemitting element was measured. Further, the measurement was carried outat a room temperature (under an atmosphere where a temperature wasmaintained at 25° C.).

Measurement results are shown in FIG. 25 and FIG. 26. FIG. 25 shows ameasurement result of a voltage-luminance characteristic, whereas FIG.26 shows a measurement result of a luminance-current efficiencycharacteristic. In FIG. 25, a horizontal axis represents the voltage (V)and a longitudinal axis represents the luminance (cd/m²). Also, in FIG.26, a horizontal axis represents the luminance (cd/m²) and alongitudinal axis represents the current efficiency (cd/A).

The light emission spectrum of the light emitting element manufacturedin this embodiment is shown in FIG. 27. In FIG. 27, a horizontal axisrepresents a wavelength (nm) and a longitudinal axis represents theintensity (given unit). According to FIG. 27, it was known that thelight emitting element of the present embodiment had a peak of lightemission spectrum at 478 nm, and emitted blue light. Moreover, the CIEchromaticity coordinates were x=0.16, y=0.28. As a consequence, it wasknown that the light emitting element of the present embodiment emittedblue light with good color purity.

Embodiment 6

A method for manufacturing a light emitting element that uses the PCABPAsynthesized in Synthetic Example 1 as a light emitting substance and anoperational characteristic of the light emitting element will bedescribed in this embodiment. Further, a light emitting element of thepresent embodiment is similar to the light emitting element ofEmbodiment 2 in a point of having a structure in which five layers arelaminated between a first electrode and a second electrode, whereinsubstances and thicknesses of these layers are different from oneanther. The present embodiment will be described with reference to FIG.15 also used in the description of Embodiment 2.

As shown in FIG. 15, indium tin oxide containing silicon oxide wasformed over a glass substrate 301 by sputtering to form a firstelectrode 302. The thickness of the first electrode 302 was set to be110 nm. Further, the first electrode was formed to have a square shapehaving the size of 2 mm×2 mm.

Next, the glass substrate 301 over which the first electrode 302 wasformed was fixed to a holder provided in a vacuum evaporation apparatus.

The inside of the vacuum evaporation apparatus was evacuated so that thepressure was reduced to 1×10⁻⁴ Pa. Then, a first layer 303 includingDNTPD was formed on the first electrode 302 by evaporation. Thethickness of the first layer 303 was set to be 50 nm. The first layer303 serves as a hole injecting layer when the light emitting element isoperated.

Subsequently, a second layer 304 including NPB was formed on the firstlayer 303 by evaporation. The thickness of the second layer 304 was setto be 10 nm. The second layer 304 serves as a hole transporting layerwhen the light emitting element is operated.

A third layer 305 including CzPA and PCABPA was formed on the secondlayer 304 by co-evaporation. The thickness of the third layer 305 wasset to be 40 nm. The mass ratio between CzPA and PCABPA was adjusted tobe 1:0.04. Thus, the PCABPA was dispersed in the CzPA. The third layer305 serves as a light emitting layer when the light emitting element isoperated. Further, the PCABPA serves as a light emitting substance.

Next, a fourth layer 306 including Alq₃ was formed on the third layer305 by evaporation. The thickness of the fourth layer 306 was set to be10 nm. The fourth layer 306 serves as an electron transporting layerwhen the light emitting element is operated.

A fifth layer 307 including Alq₃ and Li was formed on the fourth layer306 by co-evaporation. The thickness of the fifth layer 307 was set tobe 10 nm. The mass ratio between Alq₃ and Li was adjusted to be 1:0.01.The fifth layer 307 serves as an electron injecting layer when the lightemitting element is operated.

Next, a second electrode 308 including aluminum was formed on the fifthlayer 307. The thickness of the second electrode 308 was set to be 200nm.

When the voltage is applied to the light emitting element manufacturedabove such that a potential of the first electrode 302 is higher thanthat of the second electrode 308, current flows through the lightemitting element. Holes and electrons are recombined at the third layer305 serving as a light emitting layer to generate excited energy. Theexcited PCABPA emits light upon returning to a ground state.

This light emitting element was sealed in a glove box under nitrogenatmosphere so as not to expose the light emitting element to theatmospheric air. Thereafter, an operational characteristic of the lightemitting element was measured. Further, the measurement was carried outat a room temperature (under an atmosphere where a temperature wasmaintained at 25° C.).

Measurement results are shown in FIG. 28 and FIG. 29. FIG. 28 shows ameasurement result of a voltage-luminance characteristic, whereas FIG.29 shows a measurement result of a luminance-current efficiencycharacteristic. In FIG. 28, a horizontal axis represents the voltage (V)and a longitudinal axis represents the luminance (cd/m²). Also, in FIG.29, a horizontal axis represents the luminance (cd/m²) and alongitudinal axis represents the current efficiency (cd/A).

The light emission spectrum of the light emitting element manufacturedin this embodiment is shown in FIG. 30. In FIG. 30, a horizontal axisrepresents a wavelength (nm) and a longitudinal axis represents theintensity (given unit). According to FIG. 30, it was known that thelight emitting element of the present embodiment had a peak of lightemission spectrum at 487 nm, and emitted blue light. Moreover, the CIEchromaticity coordinates were x=0.17, y=032. Consequently, it was knownthat the light emitting element of the present embodiment emitted bluelight with good color purity.

Embodiment 7

A method for manufacturing a light emitting element that uses the PCABPAsynthesized in Synthetic Example 1 as a light emitting substance and anoperational characteristic of the light emitting element will bedescribed in this embodiment. Further, a light emitting element of thepresent embodiment is similar to the light emitting element ofEmbodiment 2 in a point of having a structure in which five layers arelaminated between a first electrode and a second electrode, whereinsubstances and thicknesses of these layers are different from oneanther. The present embodiment will be described with reference to FIG.15 also used in the description of Embodiment 2.

As shown in FIG. 15, indium tin oxide containing silicon oxide wasformed over a glass substrate 301 by sputtering to form a firstelectrode 302. The thickness of the first electrode 302 was set to be110 nm. Further, the first electrode was formed to have a square shapehaving the size of 2 mm×2 mm.

Next, the glass substrate. 301 over which the first electrode 302 wasformed was fixed to a holder provided in a vacuum evaporation apparatus.

The inside of the vacuum evaporation apparatus was evacuated so that thepressure was reduced to 1×10⁻⁴ Pa. Then, a first layer 303 includingDNTPD was formed on the first electrode 302 by evaporation. Thethickness of the first layer 303 was set to be 50 nm. The first layer303 serves as a hole injecting layer when the light emitting element isoperated.

Subsequently, a second layer 304 including NPB was formed on the firstlayer 303 by evaporation. The thickness of the second layer 304 was setto be 10 nm. The second layer 304 serves as a hole transporting layerwhen the light emitting element is operated.

A third layer 305 including DPCzPA and PCABPA was formed on the secondlayer 304 by co-evaporation. The thickness of the third layer 305 wasset to be 40 nm. The mass ratio between DPCzPA and PCABPA was adjustedto be 1:0.04. Thus, the PCABPA was dispersed in the DPCzPA. The thirdlayer 305 serves as a light emitting layer when the light emittingelement is operated. Further, the PCABPA serves as a light emittingsubstance.

Next, a fourth layer 306 including Alq₃ was formed on the third layer305 by evaporation. The thickness of the fourth layer 306 was set to be10 nm. The fourth layer 306 serves as an electron transporting layerwhen the light emitting element is operated.

A fifth layer 307 including Alq₃ and Li was formed on the fourth layer306 by co-evaporation. The thickness of the fifth layer 307 was set tobe 10 nm. The mass ratio between Alq₃ and Li was adjusted to be 1:0.01.The fifth layer 307 serves as an electron injecting layer when the lightemitting element is operated.

Next, a second electrode 308 including aluminum was formed on the fifthlayer 307. The thickness of the second electrode 308 was set to be 200nm.

When the voltage is applied to the light emitting element manufacturedabove such that a potential of the first electrode 302 is higher thanthat of the second electrode 308, current flows through the lightemitting element. Holes and electrons are recombined at the third layer305 serving as a light emitting layer to generate excited energy. Theexcited PCABPA emits light upon returning to a ground state.

This light emitting element was sealed in a glove box under nitrogenatmosphere so as not to expose the light emitting element to theatmospheric air. Thereafter, an operational characteristic of the lightemitting element was measured. Further, the measurement was carded outat a room temperature (under an atmosphere where a temperature wasmaintained at 25° C.).

Measurement results are shown in FIG. 31 and FIG. 32. FIG. 31 shows ameasurement result of a voltage-luminance characteristic, whereas FIG.32 shows a measurement result of a luminance-current efficiencycharacteristic. In FIG. 31, a horizontal axis represents the voltage (V)and a longitudinal axis represents the luminance (cd/m²). Also, in FIG.32, a horizontal axis represents the luminance (cd/m²) and alongitudinal axis represents the current efficiency (cd/A).

The light emission spectrum of the light emitting element manufacturedin this embodiment is shown in FIG. 33. In FIG. 33, a horizontal axisrepresents a wavelength (nm) and a longitudinal axis represents theintensity (given unit). According to FIG. 33, it was known that thelight emitting element of the present embodiment had a peak of lightemission spectrum at 487 nm, and emitted blue light. Moreover, the CIEchromaticity coordinates were x=0.17, y=0.32. As a consequence, it wasknown that the light emitting element of the present embodiment emittedblue light with good color purity.

Embodiment 8

A method for manufacturing a light emitting element that uses the PCABPAsynthesized in Synthetic Example 1 as a light emitting substance and anoperational characteristic of the light emitting element will bedescribed in this embodiment. Further, a light emitting element of thepresent embodiment is similar to the light emitting element ofEmbodiment 2 in a point of having a structure in which five layers arelaminated between a first electrode and a second electrode, whereinsubstances and thicknesses of these layers are different from oneanther. The present embodiment will be described with reference to FIG.15 also used in the description of Embodiment 2.

As shown in FIG. 15, indium tin oxide containing silicon oxide wasformed over a glass substrate 301 by sputtering to form a firstelectrode 302. The thickness of the first electrode 302 was set to be110 nm. Further, the first electrode was formed to have a square shapehaving the size of 2 mm×2 mm.

Next, the glass substrate 301 over which the first electrode 302 wasformed was fixed to a holder provided in a vacuum evaporation apparatus.

The inside of the vacuum evaporation apparatus was evacuated so that thepressure was reduced to 1×10⁻⁴ Pa. Then, a first layer 303 includingDNTPD was formed on the first electrode 302 by evaporation. Thethickness of the first layer 303 was set to be 50 nm. The first layer303 serves as a hole injecting layer when the light emitting element isoperated.

Subsequently, a second layer 304 including NPB was formed on the firstlayer 303 by evaporation. The thickness of the second layer 304 was setto be 10 nm. The second layer 304 serves as a hole transporting layerwhen the light emitting element is operated.

A third layer 305 including t-BuDNA and PCABPA was formed on the secondlayer 304 by co-evaporation. The thickness of the third layer 305 wasset to be 40 nm. The mass ratio between t-BuDNA and PCABPA was adjustedto be 1:0.04. Thus, the PCABPA was dispersed in the t-BuDNA. The thirdlayer 305 serves as a light emitting layer when the light emittingelement is operated. Further, the PCABPA serves as a light emittingsubstance.

Next, a fourth layer 306 including Alq₃ was formed on the third layer305 by evaporation. The thickness of the fourth layer 306 was set to be10 nm. The fourth layer 306 serves as an electron transporting layerwhen the light emitting element is operated.

A fifth layer 307 including Alq₃ and Li was formed on the fourth layer306 by co-evaporation. The thickness of the fifth layer 307 was set tobe 10 nm. The mass ratio between Alq₃ and Li was adjusted to be 1:0.01.The fifth layer 307 serves as an electron injecting layer when the lightemitting element is operated.

Next, a second electrode 308 including aluminum was formed on the fifthlayer 307. The thickness of the second electrode 308 was set to be 200nm.

When the voltage is applied to the light emitting element manufacturedabove such that a potential of the first electrode 302 is higher thanthat of the second electrode 308, current flows through the lightemitting element. Holes and electrons are recombined at the third layer305 serving as a light emitting layer to generate excited energy. Theexcited PCABPA emits light upon returning to a ground state.

This light emitting element was sealed in a glove box under nitrogenatmosphere so as not to expose the light emitting element to theatmospheric air. Thereafter, an operational characteristic of the lightemitting element was measured. Further, the measurement was carried outat a room temperature (under an atmosphere where a temperature wasmaintained at 25° C.).

Measurement results are shown in FIG. 34 and FIG. 35. FIG. 34 shows ameasurement result of a voltage-luminance characteristic, whereas FIG.35 shows a measurement result of a luminance ent efficiencycharacteristic. In FIG. 34, a horizontal axis represents the voltage (V)and a longitudinal axis represents the luminance (cd/m²). Also, in FIG.35, a horizontal axis represents the luminance (cd/m²) and alongitudinal axis represents the current efficiency (cd/A).

The light emission spectrum of the light emitting element manufacturedin this embodiment is shown in FIG. 36. In FIG. 36, a horizontal axisrepresents a wavelength (nm) and a longitudinal axis represents theintensity (given unit). According to FIG. 36, it was known that thelight emitting element of the present embodiment had a peak of lightemission spectrum at 482 nm, and emitted blue light. Moreover, the CIEchromaticity coordinates were x=0.16, y=0.29. As a result, it was knownthat the light emitting element of the present embodiment emitted bluelight with good color purity.

Embodiment 9

A method for manufacturing a light emitting element that uses the PCABPAsynthesized in Synthetic Example 1 as a light emitting substance and anoperational characteristic of the light emitting element will bedescribed in this embodiment. Further, a light emitting element of thepresent embodiment is similar to the light emitting element ofEmbodiment 2 in a point of having a structure in which five layers arelaminated between a first electrode and a second electrode, whereinsubstances and thicknesses of these layers are different from oneanther. The present embodiment will be described with reference to FIG.15 also used in the description of Embodiment 2.

As shown in FIG. 15, indium tin oxide containing silicon oxide wasformed over a glass substrate 301 by sputtering to form a firstelectrode 302. The thickness of the first electrode 302 was set to be110 nm. Further, the first electrode was formed to have a square shapehaving the size of 2 mm×2 mm.

Next, the glass substrate 301 over which the first electrode 302 wasformed was fixed to a holder provided in a vacuum evaporation apparatus.

The inside of the vacuum evaporation apparatus was evacuated so that thepressure was reduced to 1×10⁻⁴ Pa. Then, a first layer 303 includingCuPc was formed on the first electrode 302 by evaporation. The thicknessof the first layer 303 was set to be 20 nm. The first layer 303 servesas a hole injecting layer when the light emitting element is operated.

Subsequently, a second layer 304 including NPB was formed on the firstlayer 303 by evaporation. The thickness of the second layer 304 was setto be 40 nm. The second layer 304 serves as a hole transporting layerwhen the light emitting element is operated.

A third layer 305 including CzPA and PCABPA was formed on the secondlayer 304 by co-evaporation. The thickness of the third layer 305 wasset to be 40 nm. The mass ratio between CzPA and PCABPA was adjusted tobe 1:0.04. Thus, the PCABPA was dispersed in the CzPA. The third layer305 serves as a light emitting layer when the light emitting element isoperated. Further, the PCABPA serves as a light emitting substance.

Next, a fourth layer 306 including Alq₃ was formed on the third layer305 by evaporation. The thickness of the fourth layer 306 was set to be10 nm. The fourth layer 306 serves as an electron transporting layerwhen the light emitting element is operated.

A fifth layer 307 including Alq₃ and Li was formed on the fourth layer306 by co-evaporation. The thickness of the fifth layer 307 was set tobe 10 nm. The mass ratio between Alq₃ and Li was adjusted to be 1:0.01.The fifth layer 307 serves as an electron injecting layer when the lightemitting element is operated.

Next, a second electrode 308 including aluminum was formed on the fifthlayer 307. The thickness of the second electrode 308 was set to be 200nm.

When the voltage is applied to the light emitting element manufacturedabove such that a potential of the first electrode 302 is higher thanthat of the second electrode 308, current flows through the lightemitting element. Holes and electrons are recombined at the third layer305 serving as a light emitting layer to generate excited energy. Theexcited PCABPA emits light upon returning to a ground state.

This light emitting element was sealed in a glove box under nitrogenatmosphere so as not to expose the light emitting element to theatmospheric air. Thereafter, an operational characteristic of the lightemitting element was measured. Further, the measurement was carried outat a room temperature (under an atmosphere where a temperature wasmaintained at 25° C.).

Measurement results are shown in FIG. 37 and FIG. 38. FIG. 37 shows ameasurement result of a voltage-luminance characteristic, whereas FIG.38 shows a measurement result of a luminance-current efficiencycharacteristic. In FIG. 37, a horizontal axis represents the voltage (V)and a longitudinal axis represents the luminance (cd/m²). Also, in FIG.38, a horizontal axis represents the luminance (cd/m²) and alongitudinal axis represents the current efficiency (cd/A).

The light emission spectrum of the light emitting element manufacturedin this embodiment is shown in FIG. 39. In FIG. 39, a horizontal axisrepresents a wavelength (nm) and a longitudinal axis represents theintensity (given unit). According to FIG. 39, it was known that thelight emitting element of the present embodiment had a peak of lightemission spectrum at 481 nm, and emitted blue light. Moreover, the CIEchromaticity coordinates were x=0.17, y=031. As a consequence, it wasknown that the light emitting element of the present embodiment emittedblue light with good color purity.

Embodiment 10

A method for manufacturing a light emitting element that uses the PCABPAsynthesized in Synthetic Example 1 as a light emitting substance and anoperational characteristic of the light emitting element will bedescribed in this embodiment. Further, a light emitting element of thepresent embodiment is similar to the light emitting element ofEmbodiment 2 in a point of having a structure in which five layers arelaminated between a first electrode and a second electrode, whereinsubstances and thicknesses of these layers are different from oneanther. The present embodiment will be described with reference to FIG.15 also used in the description of Embodiment 2.

As shown in FIG. 15, indium tin oxide containing silicon oxide wasformed over a glass substrate 301 by sputtering to form a firstelectrode 302. The thickness of the first electrode 302 was set to be110 nm. Further, the first electrode was formed to have a square shapehaving the size of 2 mm×2 mm.

Next, the glass substrate 301 over which the first electrode 302 wasformed was fixed to a holder provided in a vacuum evaporation apparatus.

The inside of the vacuum evaporation apparatus was evacuated so that thepressure was reduced to 1×10⁻⁴ Pa. Then, a first layer 303 includingCuPc was formed on the first electrode 302 by evaporation. The thicknessof the first layer 303 was set to be 20 nm. The first layer 303 servesas a hole injecting layer when the light emitting element is operated.

Subsequently, a second layer 304 including NPB was formed on the firstlayer 303 by evaporation. The thickness of the second layer 304 was setto be 40 nm. The second layer 304 serves as a hole transporting layerwhen the light emitting element is operated.

A third layer 305 including DPCzPA and PCABPA was formed on the secondlayer 304 by co-evaporation. The thickness of the third layer 305 wasset to be 40 nm. The mass ratio between DPCzPA and PCABPA was adjustedto be 1:0.04. Thus, the PCABPA was dispersed in the DPCzPA. The thirdlayer 305 serves as a light emitting layer when the light emittingelement is operated. Further, the PCABPA serves as a light emittingsubstance.

Next, a fourth layer 306 including Alq₃ was formed on the third layer305 by evaporation. The thickness of the fourth layer 306 was set to be10 nm. The fourth layer 306 serves as an electron transporting layerwhen the light emitting element is operated.

A fifth layer 307 including Alq₃ and Li was formed on the fourth layer306 by co-evaporation. The thickness of the fifth layer 307 was set tobe 10 nm. The mass ratio between Alq₃ and Li was adjusted to be 1:0.01.The fifth layer. 307 serves as an electron injecting layer when thelight emitting element is operated.

Next, a second electrode 308 including aluminum was formed on the fifthlayer 307. The thickness of the second electrode 308 was set to be 200nm.

When the voltage is applied to the light emitting element manufacturedabove such that a potential of the first electrode 302 is higher thanthat of the second electrode 308, current flows through the lightemitting element. Holes and electrons are recombined at the third layer305 serving as a light emitting layer to generate excited energy. Theexcited PCABPA emits light upon returning to a ground state.

This light emitting element was sealed in a glove box under nitrogenatmosphere so as not to expose the light emitting element to theatmospheric air. Thereafter, an operational characteristic of the lightemitting element was measured. Further, the measurement was carded outat a room temperature (under an atmosphere where a temperature wasmaintained at 25° C.).

Measurement results are shown in FIG. 40 and FIG. 41. FIG. 40 shows ameasurement result of a voltage-luminance characteristic, whereas FIG.41 shows a measurement result of a luminance-current efficiencycharacteristic. In FIG. 40, a horizontal axis represents the voltage (V)and a longitudinal axis represents the luminance (cd/m²). Also, in FIG.41, a horizontal axis represents the luminance (cd/m²) and alongitudinal axis represents the current efficiency (cd/A).

The light emission spectrum of the light emitting element manufacturedin this embodiment is shown in FIG. 42. In FIG. 42, a horizontal axisrepresents a wavelength (nm) and a longitudinal axis represents theintensity (given unit). According to FIG. 42, it was known that thelight emitting element of the present embodiment had a peak of lightmission spectrum at 485 nm, and emitted blue light. Moreover, the CIEchromaticity coordinates were x=0.17, y=031. As a consequence, it wasknown that the light emitting element of the present embodiment emittedblue light with good color purity.

Embodiment 11

A method for manufacturing a light emitting element that uses the PCABPAsynthesized in Synthetic Example 1 as a light emitting substance and anoperational characteristic of the light emitting element will bedescribed in this embodiment. Further a light emitting element of thepresent embodiment is similar to the light emitting element ofEmbodiment 2 in a point of having a structure in which five layers arelaminated between a first electrode and a second electrode, whereinsubstances and thicknesses of these layers are different from oneanther. The present embodiment will be described with reference to FIG.15 also used in the description of Embodiment 2.

As shown in FIG. 15, indium tin oxide containing silicon oxide wasformed over a glass substrate 301 by sputtering to form a firstelectrode 302. The thickness of the first electrode 302 was set to be110 nm. Further, the first electrode was formed to have a square shapehaving the size of 2 mm×2 mm.

Next, the glass substrate 301 over which the first electrode 302 wasformed was fixed to a holder provided in a vacuum evaporation apparatus.

The inside of the vacuum evaporation apparatus was evacuated so that thepressure was reduced to 1×10⁻⁴ Pa. Then, a first layer 303 includingCuPc was formed on the first electrode 302 by evaporation. The thicknessof the first layer 303 was set to be 20 nm. The first layer 303 servesas a hole injecting layer when the light emitting element is operated.

Subsequently, a second layer 304 including NPB was formed on the firstlayer 303 by evaporation. The thickness of the second layer 304 was setto be 40 nm. The second layer 304 serves as a hole transporting layerwhen the light emitting element is operated.

A third layer 305 including t-BuDNA and PCABPA was formed on the secondlayer 304 by co-evaporation. The thickness of the third layer 305 wasset to be 40 nm. The mass ratio between t-BuDNA and PCABPA was adjustedto be 1:0.04. Thus, the PCABPA was dispersed in the t-BuDNA. The thirdlayer 305 serves as a light emitting layer when the light emittingelement is operated. Further, the PCABPA serves as a light emittingsubstance.

Next, a fourth layer 306 including Alq₃ was formed on the third layer305 by evaporation. The thickness of the fourth layer 306 was set to be10 nm. The fourth layer 306 serves as an electron transporting layerwhen the light emitting element is operated.

A fifth layer 307 including Alq₃ and Li was formed on the fourth layer306 by co-evaporation. The thickness of the fifth layer 307 was set tobe 10 nm. The mass ratio between Alq₃ and Li was adjusted to be 1:0.01.The fifth layer 307 serves as an electron injecting layer when the lightemitting element is operated.

Next, a second electrode 308 including aluminum was formed on the fifthlayer 307. The thickness of the second electrode 308 was set to be 200nm.

When the voltage is applied to the light emitting element manufacturedabove such that a potential of the first electrode 302 is higher thanthat of the second electrode 308, current flows through the lightemitting element. Holes and electrons are recombined at the third layer305 serving as a light emitting layer to generate excited energy. Theexcited PCABPA emits light upon returning to a ground state.

This light emitting element was sealed in a glove box under nitrogenatmosphere so as not to expose the light emitting element to theatmospheric air. Thereafter, an operational characteristic of the lightemitting element was measured. Further, the measurement was carded outat a room temperature (under an atmosphere where a temperature wasmaintained at 25° C.).

Measurement results are shown in FIG. 43 and FIG. 44. FIG. 43 shows ameasurement result of a voltage-luminance characteristic, whereas FIG.44 shows a measurement result of a luminance-current efficiencycharacteristic. In FIG. 43, a horizontal axis represents the voltage (V)and a longitudinal axis represents the luminance (cd/m²). Also, in FIG.44, a horizontal axis represents the luminance (cd/m²) and alongitudinal axis represents the current efficiency (cd/A).

The light emission spectrum of the light emitting element manufacturedin this embodiment is shown in FIG. 45. In FIG. 45, a horizontal axisrepresents a wavelength (nm) and a longitudinal axis represents theintensity (given unit). According to FIG. 45, it was known that thelight emitting element of the present embodiment had a peak of lightemission spectrum at 476 nm, and emitted blue light. Moreover, the CIEchromaticity coordinates ware x=0.16, y=0.28. As a consequence, it wasknown that the light emitting element of the present embodiment emittedblue light with good color purity.

What is claimed is:
 1. (canceled)
 2. A light emitting element comprises:a first electrode; a light emitting layer over the first electrode; anda second electrode over the light emitting layer, wherein the lightemitting layer comprises a carbazole-containing compound, wherein thecarbazole-containing compound is synthesized by using a compoundrepresented by the following formula,

wherein R²⁰ is a substituted or unsubstituted aryl group, and whereinPh⁵ is a substituted or unsubstituted phenyl group.
 3. The lightemitting element according to claim 2, wherein R²⁰ is the unsubstitutedaryl group.
 4. The light emitting element according to claim 2, whereinR²⁰ is selected from a phenyl group, a biphenyl group, and a naphthylgroup.
 5. The light emitting element according to claim 2, wherein R²⁰is the unsubstituted aryl group selected from a phenyl group, a biphenylgroup, and a naphthyl group.
 6. The light emitting element according toclaim 2, wherein Ph⁵ is the unsubstituted phenyl group.
 7. The lightemitting element according to claim 2, wherein the compound isrepresented by the following formula:


8. The light emitting element according to claim 2, wherein thecarbazole-containing compound includes an anthracene skeleton.
 9. Alight emitting device comprising the light emitting element according toclaim 2 in a pixel portion.
 10. An electronic appliance comprising thelight emitting element according to claim 2 in a display portion.